Oil pump issues....

I have a 408 stroker from a 1978 360 block. My problem I am running into, is that the multiple Melling oil pumps I have tried, are not clearenced for ARP rod bolts and touching the main cap bolt. This causes the oil pump to sit ****-eyed and a gap where the two pieces (main cap and oil pump are machined) come together. I have talked to Mancini and Hughes Engines, and no one seems to have ever run into this. Has anyone seen this before? I bought the engine second hand from the original owner and after having it freshened up during the off-season. He ran it for over 17 years and was freshened up every couple of years.

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