I fully tuned a 501 two years ago in the UK. guy lost his job and then had to break it - well least he thought that that was his only option.
what is there to know? you can bore yours out to a 550. you can fit a cam, bigger valves, keihin carb, there are several exhausts out there all getting old now. FP and Doma are but two of those to choose from. a 41mm keihin is the more desirable one to choose from?
if strictly racing you can go for a MX ignition and flywheel. I set up a 470 for a budget hill climber in the west country and he cleans up with pretty much the above set up!
regards
taffy
