I gotta be honest, I think you're barking up the wrong tree with the axles. Assuming you have a big tripod transmission, you could put in mid or late axles and not care. You could not use early axles, but they're for small tripods anyway, so it doesn't matter. You do want the late, long axles (LH:8990731-> 4106159, RH:8990749) as those are technically the only proper axles for an '88+ car. But, the mid/late axles are separated by something like 6mm, barely anything. But, any 1988-1993 axle is what you want
The a-arms never changed. The outer CV and steering knuckle changed only to accommodate ABS, not dimensionally. My '85 SPG has a '92 transmission, '90 tripods, '90 axles, '90 knuckles, '91 or '92 outer CVs.
Literally just took this photo:
A pair of axles from a late '87 SPG and a pair of axles from a '91 900T convertible. They are the same lengths, same tripods. Only the outer CV changes for ABS.