Do you guys know if a shoc from a 1990-1991 would fit an 88?

 

I would say no...
1987-88
SHOCK ABSORBER, RR.
(SHOWA)
676065
(57683-001) $744.73

1990
SHOCK ABSORBER, RR.

676085
(57688-001) $682.18

I got this info off of bikebandit.com

But I am going to try it over the winter months to swap the rear shock of the 1987 and put in a 1990. And If it does then I will order the Olin's rear shock and the front springs.