I recently had to replace the bearings in my crankshaft as well as the rear main seal in my 72 Ford 390. While I had the engine out I replaced the oil pump with a OEM replacement, new timing chain and gears (went to steel) and did all the gaskets. I checked the oil pressure/pump before putting the engine back in and it functioned without any issues or stiffness. Twice now I've sheared the pin in the distributor and I can not figure out why. I replaced it after the first time because I figured the pin was just wore down.