...is the relief spring in the pump a candidate for stretching also?... just curious about the shim for one but not the others or stretching vs shimming
I don't know for sure, haven't been in there yet. But I've read several times of people adding a shim to the pump...probably easier and you have more control like that with thickness.
I don't want to go nuts with a lot of oil pressure...and 80 psi for the 8,000 rpm I want to turn in another project may be a little too much for a Subaru, as they seem to take it well. But how much load is on the motor plays a big part in what oil pressure you need.
What's clear is not one weight is right for all. All aluminum expands more than cast iron when hot, plus, the clearance differences from one to the next can be a big difference. For example, main bearing clearance could range from .0008 to .003, and still be in spec.
The most oil pressure I've ever known about in a piston engine is 200 psi with 70 weight oil. But that's in an NHRA Top Fuel Dragster making 1000 hp per cylinder...