Appreciate the input, and to Cab's point, you can see the marks on the crank from the rod bolt(s). It's got a race history, and I was told by the guy who owned it after the racer that the motor spun a rod bearing. It's obviously been apart before (the rod caps are ground for balancing, not the oil pan). Likely it was repaired/assembled in a hurry and never corrected.
I nicked the crank with a rod bolt on the first engine I ever built, the machinist (way back, racer from my hometown and former partner of Jon Kaase before Dyno Don fame) said to carefully use a stone to smooth the edges of the crescent-shaped gouge and run it. I did just that and the 289 has been together since 1977 with no related issues.
But- seeing the pits on the bearing makes me think that the oil got acidic while it slept for 27 years and ate the bearings. I didn't pull any other caps but I'd expect to see the same thing. I think the safe play is to tear it down.
Oh yeah, I should have done this long ago but it just occured to me- I have a copy of the Plymouth Service Bulletin # 66-45 dated January 14 1966. Under Engine Lubrication it says Oil Pump Operating Pressure @ 1000 RPM should be 45-65 lbs. So there's the factory spec for 1966 Hemi oil pressure.