It would help us understand your point here if you gave us a run down on the ford oiling system for comparison. Is it similar to the sbm and is it possible for the ford engine to have the same compatibility issues with differing brands of lifters. Other wise you are just saying he does not have the lifters adjusted correctly which he already says he has tried differing ways.
I would agree with what you are saying if we could verify that the Op does not have an oil pressure leak at the lifter bores because of incompatibility issues already raised.