Big end rod width on 3.2/3.3?
 

According to Wayne's book, in 1986 Porsche changed the big end connecting rod width from 21.70-21.80mm to 21.85-21.90mm and they closed up rod sidewall clearance from .200-.350mm to .100-.200mm. Would it be safe to assume that a replacement rod for any 3.2/3.3 from 78 on should be the wider rod that closes the gap?

If the side gap is too small, proper rod bearing oiling is impaired. That said if the factory reduced the gap, your assumption seems sound.