So far I have been using the "revisedquestbooks" published by slev. I am not using his ruleset yet but just his questmaps. They look more balanced and difficult for the heroes. I gotta check out his rules later.
I am writing this out here as a guideline for myself, cause I want to connect the quests and work in some extra missions for the terrain and outside boards where they fit.

Work in progress!

Storyline - A Gathering Storm:Introduction/Setting the scene: The four adventures have heard the call of the great wizard Mentor and headed to Nuln to meet him in his tower.
This is where the story begins...
1. Rescue of Sir Ragnar The intro takes place in Mentors tower outside of Nuln from which the heroes have to travel east to the area of Drakenhof Castle to find and rescue Sir Ragnar. (Nuln, travel, Outsideboard, HQ Board)
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Intromission to "Lair of the Orc Warlord" - The Caves Of Ulag! After the rescue of Sir Ragnar Prince Magnus has ordered that the Orc Warlord Ulag should be sought out and killed. Ulags stronghold is in "The Caves of Ulag" located below a secret passage on Black Fire Pass within the Black Mountains. Mission starts at Nuln, travel north down the old Dwarf Road and to Black Fire Pass. As they reach the Black mountains the Heroes gonna meet an NPC who informs them about missing children in the area, as they meet him at Black Fire Pass looking for his kidnapped daughter. He holds the information to the secret passage that will let them avoid traversing the difficult forest terrain and avoid the Orc mountain patrols. After finding the secret passage through the mountains and avoid the patrolling guards their mission is to make it through the caves alive, avoid or use the Fimircage traps, use the secret door triggermechanism and find the entrance to the Lair of Ulags Dungeon. (DnD Session)
2. Lair of the Orc Warlord:Heroquest Board
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Intromission "Finding the Orcs Hideout" (Mountain Road Map, Outside Board) After the killing of Ulag the emperor puts out a reward to return his treasure stolen by a band of Ulags Orcs hiding in the Black Mountains in the south, south of
Kroppenleben.
3. Prince Magnus Gold:Hero Quest Board
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Intromission "Finding the Maze" (Ancient Forest Map, Underground tunnels) Quest to find the Talisman of Lore within Melars Maze, near Karak Norn in the Grey mountains in the south.
4. Melars MazeHero Quest Board
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Intromission "Heroes gettin captured" on their way back from Karak Norn (Ancient Forest Map, Outside Board)work in progress
5. Legacy of the Orc Warlord Ulags foul offspring, Grak has captured the heroes and is holding them prisoner in his dungeon. The heroes must escape his stronghold, north of Black Water Lake. Hero Quest Board
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Intromission "Finding the secret lab" (Ruins board) After their rescue the heroes learn that the Emperors personal Wizard has disappeared. They have to find out what happened to him and bring him back to safety if alive. The quest takes place in a secret lab in the catacombs under Altdorf.
6. The Stone HunterHero Quest Board
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Intromission "Finding the Canyon Lair" (Cavernous passages)The Orcs in the Black Mountains have been using fire magic in their raids. Balur the fire mage is responsible for helping them. The heroes are chosen to enter his lair beneath black fire Crag, a small canyon section of Black Fire Pass
7. The Fire MageHero Quest Board
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Intromission "Getting Trapped" (Ye Ol Inn Board, getting lured into mission) work in progress
8. Race Against Time After Balurs destruction the heroes get lured into a trap, into a dungeon that was rumored to hold a great secret. They have to escape. The location is near the Mount of Krell. Hero Quest Board
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Intromission "Finding the Clue" for the castle on their way back (Haunted Forest map) work in progress
9. Castle of Mystery After their escape on their way back they find out that long ago a great wizard named Ollar has discovered the entrance to a goldmine and build a magic castle above it. The lure of gold leads the heroes to find this castle which is located at castle Drachenfels.
Hero Quest Board
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Intromission "Finding the Underground Fortress" (Cavernous passages, cavern, lake set) The lands to the east have been plagued by Orcs and Goblins, the emperor has ordered their destruction. They are rumored to be in a strong underground fortress known as the bastion of chaos, held by a band of chaos warriors. The stronghold is located at Karaz a Karak southeast of Black Water Lake behind the Black Mountains.
10. Bastion of ChaosHero Quest Board
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Intromission "Finding the Catacombs of Verag" (Ruins Board) The Trial to become Champions, the heroes have to travel east from nuln and enter the catacombs of Verag a foul gargoyle who guards the tomb of Fellmarg, located in the Black Mountains, at Blood Peak.
11. The Trial After the heroes have defeated the gargoyle and have been granted Champions. Gonna change the original hero minis for the Litchmyre minis at this point as their leveled up characters ! Hero Quest Board
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Intromission "Finding Barak Tor" (Cavernous passages, caves) work in progress
12. Barak Tor - Barrow of the Witch Lord Quest to find the ancient star of West, a gem rumored to lie in Barak Tor the resting place of the Witchlord, known as the king of the dead, who has been destroyed by the Spirit Blade long ago. Barak Tor being located in Karak Azul deep in the south, in the mountains east to the Badlands. Hero Quest Board
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Intromission "Entering the Fire Mountain" (Cavernous passages leading into Lava Caves) The heroes have awoken the witchlord, to destroy him the heroes have to find the spirit blade which is rumored to be located at the edge of the Fire Mountain, east of Karak Azul
13. Quest for the Spirit BladeHero Quest Board
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Intromission: Finding a new path through the Firemountain back" (Lava Caves, Dragonboss) work in progress
14. Return to Barak Tor After having found the spirit blade, the witchlord has to be defeated in his dungeon, in Barak Tor, located in Karak Azul. Hero Quest Board