G`day i need a bigger /faster motor for my wasp 1976 (stock xs650) happen to have a water cooled gpz900 motor(1984) which looks like it would be a nice fit.would this motor be legal in a pre85 outfit? I like the idea of a stock big motor rather than a hotted up xs650.reason i am 138kg passenger 80kg so i am giving up to 60 kg advantage to the other bikes .