Oil pressure relief valve woes? Options

[ahdoman]

OK, here's the symptoms...
extremely high oil pressure readings when cold (about 120psi) and still high when up to temp (about 90psi) while driving. I know the gauge and sender are working because the oil PSI will vary with engine RPM (about 30 PSI).

Engine details...
2.0 carbed w/ hydraulic lifters, Royal Purple 10/40 and Mobil 1 filter.

I assume the problem lies in the oil pressure regulators? Any other ideas before I begin surgery?

So, here are the questions...
1) Do I need to drain the oil before I remove the pressure regulators?
2) Do I need to remove both regulator assemblies (Haynes reference; 15.4 & 15.5 page 29) and if so what do I replace?
3) On page 20, section 6 of the Haynes manual point #2 says "oil goes to a cooler which again has a bypass valve" - Is there another valve actually in the cooler?

Extra bonus question for hydraulic lifter experts...
On the later bus cases I remember hearing that they eliminated the pressure valve on the right side of the block? My understanding was to provide greater oil flow to the lifters. Is this true and if so do I actually need that valve in place or did I completely get that wrong?