I'm beginning to know how that little AFLAC duck must feel.
That 9RS3-0765-TFC compressor is actually a triple-rated pump........applicable to LT R12, MT R12 or XLT R502. Granted, if you have an R12 LT system with this compressor on it you won't be able to set a CPR valve by the "RLA" stamped on the pump (if it's old enough to have a Copeland RLA) because you'll likely never reach it. Ergo.....you don't need the CPR in the first place.
While I have the ability to hop in the truck and get all the Copeland data instantly from my laptop from Calculator program, how many guys have that available to them out here? If you call your local "Primesource Wholesaler", if your lucky there's one guy who may understand what info your asking for and knows how to give it to you quickly and accurately.
For the most of us in the field, the compressor RLA that's stamped on the unit is the best it's going to get for setting a CPR to prevent motor overload. Sure, there are techs in the field who don't have a clue as to what that valve is there for and then they usually guess wrongly that it's an EPR.
We have to agree that when setting the valve, motor amps are what you use to do it. Both Sporlan and Alco say this. How you get the amps to set it to is the question to be answered. As for me I'll stick with using the RLA value stamped on the unit unless of course I run across an antique system with a 9RS3-0765-TFC R12 LT on it.