I think the difference in the arms themselves is the 87+ arms don't have a bumpstop location cast in them. But yeah, you can put an early hub on a late arm and have the same offset increase of the early alloy arm (+44 instead of +65 or whatever).

For now I will just be using the stock IRS arm and the NA mounting plate, but with the turbo caliper(either 944 or 993) and Boxster rotor to limit my offset increase to +22.

I thought so too but my alloy's have the bumpstops and the big hubs/rotors. I already have all the NA brake bits to use on IRS arms too. I'm just waiting on Lanner to work his magic on a set of spindles. Here's a couple my 951 calipers that prettied up:

Nice. Where did you go to get those done? Paint or powdercoat? I would like to do the same with mine, but either stay with black or go with blue like my interior and fender beading. I think blue with white Porsche script would look nice.

I did it myself, ground down all the raised casting, sprayed it with VHT caliper paint baked it, then used a stencil and painted the lettering on. I found a DIY on a Porsche site and that is what they recommended.

Those are very well done Nick. Nice.

Wow great job on those nick