It's a long story, but in short.
The frames were replicas of one that we came upon which was damaged (badly). The one I built didn't handle too well (30* head angle) and at the time I assumed the builder could make me another and just tighten up the steering head a little. I still have enough parts to build another, excepting the frame...
The builder of this particular replica frame is still kicking about, trying to sort everything and catch up on his workload. One day....
Of course, you can extract a LOT of reliable power from the XT/TT lump, but it's 10lb heavier than the BSA/CCM donk.