This is the exact same problem that I experienced on two occasions with the same engine, first time was with a dry sump and second time with a wet sump. I've done exactly what you did, spun the oil pump and the engine and was shocked at how much oil is pumped up out of the lifters. I found that changing from solids to solid rollers increases the oil to the top of the engines due to the built in restriction that is in the solids, but not in the rollers. Rpm's compound the problem. I just picked up my block from the machine shop and I had ALL of the lifter bores bushed to restrict oil to just them and now it should hold more down into the bottom end. I am going to eliminate the restrictor at the rear main as I am using only a .030 hole in each lifter bore to meter oil to them. I'll know after I get it put back together! I also measured the diameter of the lifters and found that the solids are .875 and the rollers are .874. More clearance in the lifter bores equals more oil coming out of the lifter as the holes in the rollers are freakin' ginormous!!!