gpz swingarm questions...need wisdom...

Looking for a slightly longer low-profile swingarm for my '83 Uni-Trak GPZ550.

Would anyone know the dimensional differences between the 550, 750, and 900 swingarms?

Does the shock mount in the same relative position between models? If so which are compatible/not with the 550? Linkage?

Considering the age of GPZ shocks, would like to upgrade, esp to something that has some sag/height adjustment...GSXR?

If GSXR...since shock is made for the GSXR swingarm, would I be better off just going with the components that were engineered for each other? And finally...if so what model/years?

Thanks everyone!


mx4life