nope, looking for spare rear hub myself, ebay has em but more than i will pay for a spare!
With your 500 in a side car, CUBES will be the go surely? I rode a 465 with a 3mm stroke increase 30 years ago, i still remember what it was like, it was also ported, WAY too much power, they ended up putting stock-ish barell back on it and it was nice then, but i was still quicker on a stock engine. GO the stroke route and try, it boosted the 465 bottom and mid up a fair amount and then maybe some porting after that. Personally i dont reckon i would use a rm500 motor, parts are getting hard to find, i would go any of the other japs given the choice, trouble is i have Yellow in my blood, well yellow, green and now Maico!
If you hve your 500 head off, any chance of getting me a chamber volume? in ML??
Kt.