Axle not centered in car

[chicane]

I would say that you need to measure both the body and frame... and see where the discrepancy is first.

Was the differential centered before you did the bushings ?? Do you know if the car has ever been in an accident ??

Looking for the "easy way" doesn't necessarily mean the "correct way" to solve your issue. I would not recommend moving the spring perches... nor would I ever recommend using a different offset for a single wheel... those are just band-aid fixes that do not solve your issue.