I bought a cast iron 4.490 rough bore cast iron wedge World block from my local Dodge dealer several years back when they where still available, I had that block machined last year and I built it for a customer last year, we had a issue with the current model B1 valve covers not clearing a MSD billet distributor properly last year that was discovered while attempting to dyno it. I bought some original B1 valve covers from a member on here and went back to the dyno on Monday to test and tune it, the motor had started and ran fine for short while warming up the oil and water before twisting the oil pump drive rod off while running due to the oil pump gear hitting the cover I had no problems priming it on the engine stand either time, no problem with any of the Milidon oiling system parts, it took a while to figure out the root cause which was the block wasn't machined completely flat and properly on the oil pump mounting pad mating surface It had a very small thin ridge that was around .012 to .018 raised above the oil pump mounting surface which ended up pushing on the bottom of the pump pinching, raising, the oil pump gear up against the pump cover eliminating the end clearances
My message is if you have one of those blocks look very closely at that surface, especially if your going to use the Milidon 21815 oil pump using the two O rings and no gasket
What a pain in the rear which ended up causing us to use up most of one day on the dyno identifying the cause and resolution
IHTHs some one else to avoid this same issue