I was going to mention that yesterday, when you said something about a center oiler, and then talking about hydraulic roller lifters, etc. I have seen some center oilers that were drilled from the factory, but most are not, maybe some of the boat blocks were? I run an old beat up center oiler like yours. My lifter galleys were not drilled from the factory like yours. I am running BT high riser heads and T&D rockers, that oil through the push-rods. So I had those two lifter galleys drilled, and then connected the side feeds to the top oil galley. I blocked the oil to the top at the deck, for the normal OEM rocker oil path. I put a restricter in the cross feeds, and tapped the top for pipe plugs. I used Morel Ultra Pro solid roller lifters. Runs and oils fine that way, so you can plan ahead, and drill those lifter galley's, and then you can do whatever you want later if plans change.