So today I test fit an old F2 engine. I have an F2/3 that I've been learning on for the past few years. Then I picked up another on the cheap and fixed it also. With all of the cbr parts I have, I thought I could find another but somehow I ended up with a GS500. Obviously, I'd try to insert cbr600 engine right?! For people searching to see if this will work:
nope. Not without modifying the front frame for the exhaust. The rear wasn't too bad and you could fab some brackets but the exhaust was the dream killer.

So, back to my gs500 engine. PO didn't give me the piston assembly, so I'll have to locate that before I can start putting things back together.