Finally installed the ZZP Oil Volume relief spring and piston.
Removing the oil filter housing was tough. The top two bolts are extremely difficult to access. I could only get one flat turn at a time turning the wrench each time.
Thanks for the tips Pdad.
Running with 5W30 Mobil 1 now.
Notice the oil pressure gauge is reading only one notch higher now. Doesn't appear to be making much difference.
The new spring is only 1/16" longer that the original spring.
Still running with the 3.2" pulley. Making an honest 10 psi but I think the gauge is reading 1/2 psi low.
I will save the 3.1" for the dragstrip.
Hopefully I've just added a bit of insurance.