Time to let the cat out of the bag....
My winter project is making this NSR-D 350 beast. Still got loads to do of course but the engine's in there properly now, which was the major hurdle. I've basically got the wiring to finish off (RD loom) some pipes to make, carbs to fit'n'fettle, lights (possibly) and ponder the fairing/sundries/paraphernalia etc.... oh and paint it...
I'm not claiming it'll be in anyway better than a stock '21, and I've forgotten the reason I started it, but it should be an 'interesting' ride all the same. And prehaps even a bit of inspiration for your 500 project Fenton?