Audi and Mercedes wheels are "hubcentric" mount, meaning the center hole flange is load bearing. The Audi center holes are smaller than the Mercedes and would have to be machined larger to fit.

The FPR is different after the 1984 model given the differences in the M102 engine after '84, and is different for auto and manual transmissions.

Swapping to a "newer" 102 engine may be slightly problematic (ie. expensive) unless you have a donor car parked next to it . . . and if you did, I'd restore the donor car instead.