I bought a different rear head when I put a Sanden on my 1985 M-B 300D. There were about 20 different choices from a vendor on ebay (with photos), all ~$20 each. That was for an SD7 Sanden (7-bolts). If you have the earlier 5-bolt (SD508? recall), might not be those choices. In my case, I needed the rarer "GM Pad" head (about 3 versions for that). Most common is a head with #8 and #10 O-ring ports, which sounds like what RRR needs and those have at least 2 versions with ports coming out either axial or radial (most common) and might even have those in mirror-image (swap left & right). You can also **** a Sanden angularly just shy of 90 deg off vertical. The mounting ears are the same except for the H13 "shorty" which has the front to back flange spacing ~1" closer. I recall SD508 have same mount ear geometry. Most common is the H15 (SD7H15).
I had an H13 (OE on Civics?) on my M-B for more rear clearance, but the custom bracket cracked apart (made by a forum member) so went back to the OE Harrison R4 compressor (GM used in 1980's), so now have the H13 on my 1964 Valiant 225 (made custom brackets). The R4 (5 one-way pistons) seems to cool as well as the Sanden did (7 double-acting pistons so 14 puffs per rev). I doubt you would see much improvement with an SD7 over a York and wouldn't save much weight since the York is an aluminum body (2 one-way pistons?). I have a York on my 1965 Chrysler (aftermarket kit, Sears, Western Auto, or dealer?). If you think the RV2 is a beast, my 1965 Dart came with a Tecumseh compressor as a retrofit. That has the same dimensions as a York but in a cast-iron body and a larger diameter clutch, so might have been heavier than an RV2. Yes, it had cracked the aftermarket bracket. Sold it to a guy cheap to mod for an off-road air compressor.
Perhaps most important for better cooling is having a large parallel-flow condenser, with perhaps an electric fan to aid in stop & go traffic. I use Duracool refrigerant in all my vehicles (even 2002 Chrysler after a compressor failure), which works slightly better than R-12, with PAO 68 oil which works with all refrigerants (R-12, HC, R-134A) and doesn't absorb moisture like PAG (bad, forms corrosive acids). It is also claimed more efficient, since stays more in the compressor rather than coating the condenser and evaporator tubes.
