Like most game tiles, such as Dwarven Forge, Dungeons and Lasers uses a 2" x 2" footprint for its tiles. HQ has 1" passages and rooms with odd-length walls. So you have to kludge a bit to make a board.
You'll need multiple sets of fantasy core tiles, and sewer core tiles, at least two fantasy core sets (and even then you'll only be able to create the rooms you need for the quest, rather than the entire board).
What I did was start with the map of a quest, and expanded the rooms to fit the 2x2 square tile size. I would then fill in the rooms with terrain to reduce the space in the room to that matching the map.
Second pic has notes on the map how I'd modify the rooms. The outer passage uses the Sewer Core Set tiles.
Spoilers ahead, not that you haven't played this quest a few dozen times...!