Basically, it's going to be based on the bike I always regretted having to give up -- my old Peugeot Orient Express, which had the most beautifully medieval lugs and fork crown ever, and which served me well until I tried to convert it into an Xtracycle (the Peugeot frame was 21", already a little big for me; so when I converted it it became too tall for me to ride safely).
The new frame, a 1986 Specialized StumpJumper, is much lighter than the Peugeot. At 19.5" center-to-top, it's slightly bigger than what I've been riding, but set up with upright bars that shouldn't make a difference. It also takes a rear U-brake (or, more specifically, a SunTour Roller-Cam brake), which tells me it's a Team StumpJumper model.
I have two options regarding the brakes: I can try to source parts to run it as intended; or I can pay a framebuilder to move the rear braze-ons to the seat stays so I can run regular canti brakes in the rear. I'm inclined to make it work the way it came if possible.
(And LOOK at those pretty lugs!)
I have quite a few parts on hand already to build this up, which made the decision to get it pretty easy. My only issue is that I will need to find a new source for used parts. Probably will hit up the Bike Farm and see what they have.
It will be nice to have something to putter on. I promise pictures when it's done.