What a sexy bike Marc. It would look much better in my shed though.
I saw what looked to be a `78 or `79 CR frame with an XL/XR motor in it down in tassie last year at the nats. The motor was painted in the original CR red and it looked an absolute treat. Shame it was kept on the back of the ute in the carpark!
Ive also seen an XR350 motor shoehorned into an '84 CR frame which looked like a good fit as well. Why the 350 and not the 500 is beyond me though.
I really want to build up a decent pre80 thumper and would love a C&J or White Bros. frame if anyone can help. If not, I might have to sacrifice a 79 PE frame to fit the 79 XR500 motor into.
At the end of the day, all thats required to fit a motor into a frame is a bit of imagination and alot of $$$$
Then theres the time needed to sort it into a bike that works...but thats the fun bit!