OK - I tried and tried to sell this project, with no luck which shocks me but so be it. The frame is up to USD$1600 from Voodoo Vintage these days which isn't much lower than the price I was asking for the full project.
Anyhow - I'm digging back in and am nearly complete with the engine assembly (clutch etc. was all still off) and I'm sorting out a set of carbs. Sprockets, chain, throttle, cable etc. are all on order.
I'm working towards getting the motor running, but will start tacking mounting tabs onto the frame for foot pegs, fender struts and seat mount in the next week or two. Once I sort out a fuel tank and battery/electronics box, I'll get those mounts sorted then take the frame in for professional TIG welding.
Once I have the sprockets and chain, I can line up the rear wheel and get the spacers machined for it. My eyeball tells me the stock XS right side spacer puts the wheel dead centre with the sprockets aligned, but need the sprockets and a long enough chain to confirm.
Front wheel brake hub needs to be machined out to 17mm to fit the axle and then I can stack some washers in there to center it / have spacers made up.
Exhaust will be tricky - will try to find some junker headers around somewhere and see what works before I go ahead and try to make one or order something.
I'm hoping things sort of fall into place now that I've emptied a couple of boxes of clutter getting the engine back together and get some of the fiddly bits taken care of.
I've been pleasantly surprised at how quickly I've found all the tiny shims/springs I needed to put the starter gears and clutch back on.