I run 1.25" spacers in front and back on my 83.  I have ran 36 SSR's and now I am running 35" yokohama's .  Little rubbing on the fender well  but a sawzaw will solve that problem.  You should be fine with the 1.5" spacers though even with the back spacing.  Anything above 1.5 I think would run you into some rubbin issues.    Wheel on!