Other than using some odd-ball non-GM washers, there are only two settings. 6+6 and 9+3. I guess you could put both 6's or the 3 and 9 on the same end that would give you more/or less caster. I haven't seen a pre-88 that needed different pairs on the left and right. I'd be curious if anyone else has. Roger, do you see that very often?
From the factory they were marginal on caster as it was, so invariably the caster has to be increased and that's why the 9+3 kit exists (a few other cars use the same kit. Chevette is one).
I'm curious if any had 3+9mm washers from the factory.
Either way, when ever I rebuild a front end I get the 3+9 kit and run the top arms back. The caster is always in spec and falls between 5-7 degrees. If not, something is usually bent. Not that I've done very many mind you. 5-6 there-bouts.
In the end, only an alignment will tell.