I'm not understanding who's doing the engine building. Are you reworking the same engine each time? An experienced builder should not have missed the contaminated oil heater and it should have been ditched with the dry sump install. Was everything vatted? And why no oil cooler? I can't believe the oil was not getting very hot.
While I'm being critical, you should have everything checked before building it again. Check the crank and rods. Bolt the case together with torque plates or heads on and check journals for straightness, roundness and size. It may need to be line bored if it's never been done and it needs to be done the right way, with torque plates in place. Changing from stock studs and adding higher torque will distort the case.
Best of luck. Thanks for sharing.