with enough money you can do anything. seriously it would take some time and money to make a cr shock fit. then you would have to modify or replace the forks to balance out the suspension. It can be done, but it is a little more involved than most people want to mess with.
You weren't born knowing this stuff.
I had a Works rear shock on my XR200. It did improve straight-line suspension, but the bike still responded erratically to side hits (not squaring up on an obstacle would still make the bike veer off in a weird direction). I finally came to the conclusion the chassis was flexing. Not much to be done about it.
If you want better suspension, but love the XR 200 powerplant, I'd suggest a conversion to a CR chassis. It would be about as much work as installing the shock, but the result would be a much better handling bike. I've ridden a few of these, and they're really nice.
[This message has been edited by DualSportr (edited 04-08-2001).]