I've already decided I don't trust this engine, and it's replacement is in the works (thanks Pendy). But I'd still like to better understand what's wrong with mine. I drilled a hole in the oil pressure sender and tapped a thread to match a oil pressure sender I bought at pep boys. I hooked it up and got the following readings:
Cold: Idles and about 30 psi, went up to about 35psi on the road.
Hot: Idles at about 20 psi (maybe 19), and ran about 30 on the road.
From what I have read here this seems pretty good, although I don't know if these gauges are reliable or need calibrated somehow. Maybe I'll get my friend Loic to try it on his truck as a reference