Not sure you should take off the forks since they kind of define the look of a T500, unless theyre bent or damaged in a non repareable way. You can probally get modern damper cartridges and teflon bearings to go in to improve them discreetly. If classic is what your building to, cant beat external spring forks, set o bacon slicers and a big old robinson 4ls front brake with scoops and front numberplate. Even if it will overheat and fade after a few big stops
For the conversion itself, how I would have approached it was I would turn up a new yolk spindle in your lathe to take the same bearings as the original stem, and push out the the V50 stem from the bottom yolk (theyre usually welded in, so if you grind out the weld, they push out downwards on a big press) and push in the custom one. It would cost nothing but time and materials and would be strong and take oem parts when it comes to replacement, and you could avoid all the shimming and cutting.
For the bearing, cutting down the outer race, arent they all hardened? you mentioned red chips, does the race itself heat up during the turning operation enough to destroy any heat treatment they did on it?
As a aside, my bimota has eccentric rings in the headstock around the bearing so you can alter head angle by loosening the locking nut and rotating the eccentric. Clever but how many people are going to be tuning their handling enough to want to alter head angle in the pits. I havent played with half the adjustments on it, and Ive been riding it for years now..
For the wheel, you could probally get some bearings off the shelf that fit the housing on the wheel and are 2mm bigger id.
Used to have a K4 on the road, better hack than a superdream anyday!
