Seems to be very little info on anything 250. I guess it wasn't big in the States as there's loads more for the 350. Maybe brits are just restoring them and not customising. Mine is missing side covers, air filters and the filter housings, and it'll be hard and expensive to track them down, so it feels like a perfect donor for a custom build!
At present I'm gonna do the same as you, but if mods look hard to do with the 725b, I may have to save up for the mikuni's.
Anyway, I find having a deadline to work to sometimes energises you to get stuff done, so sure you'll get it all sorted in time. Chuffed for you that they wisely saw fit to include a true shed build in the show. See you then!