[Jac Mac]

Have you removed the rod bearing caps to inspect the rod bearings yet, oil in the pump rotor means nothing, once the pumpdrive sheared what oil was on pressure side of pump would just stay there.
I dont bet on motors , 'do it once & do it right', my advice , forget about 'Eric' or whomever did the first build & find someone who is conversant with the engine, or at least someone who is prepared to do the research & take the time to learn how to do it right, be prepared to be patient & pay that person a fair amount for his time. looks like you might be needing his services again in the future
The number of 'non compatible' parts & bad engine building practices in the initial build of this motor is just 'bad', no other way to describe it! One other thing, when an oil pressure gauge drops to zero, or a temp gauge ,goes of the clock', It means stop now, right now & find out what the problem is, DO NOT DRIVE HOME thinking what might be the problem. In forty plus years of motoring I have never seen an oil pressure problem get better by doing a few more miles........

Hope I have not spoilt anyone's sensitivities with that piece of wisdom