I toyed with the idea of getting a 6.3. The idea of driving one of those beautiful, powerful machines was seductive for awhile, but after a bit I gave in to the reality that they are moneypits. I went a got a nice 450sl instead. It's still a moneypit, but a much smaller, friendlier one that I can work on myself
Anyway, check out this link, it has some good info on the 6.3
www.mbz.org/info/articles/misc/cheap63.html
Also,
http://www.m100.org was very helpful, but it doesn't seem to be up right now. Good luck!