Hi Bob
Blocking of the oil feed to the rock assembly was easy just unscrewed the line from the fitting in the middle of the assembly and replace it with a union fitting that had the end soldered up.
You can just see it sticking up between the push rods in the center of the picture.
Yes I had taken note of the instructions about the gaskets on the oil pressure relief on the side of the engine. Took it apart and checked that I had assembled it correctly. As to the restrictive orifices yes I've learned to look at the fittings on the Chevy both in the oil system and vacuum system. When I find them I tag them, made a number of replacements over the years by soldering the replacement closed and then drilling it with a matching size drill.
Your suggestions and comment have been very helpful as the process of communicating back and forth helps the diagnostic process. As does making incredibly dull videos because that way I can refer back to the video.
I'm pretty sure that I have exhausted the easy things to check and that what ever it is going to take some real time to find.
Cheers Phil