Gotta build ANOTHER engine.

I was initially getting p-v contact with my build but that was due to the lifters being fully pumped up and the pushrods being slightly too long, once I got shorter pushrods I could assemble the rockers and slowly rotate the engine so the spring pressure would bleed-down the lifters.

Wouldn't spinning the oil pump pump the lifters back up? I've also been searching around and i've seen a couple people mention they ran cams slightly bigger than mine on a stock Magnum short block with no P-V clearance issues.

I guess if I really want to get this right I gotta hit the junkyard and grab 2 more lifters to convert into solid testers.
I've never worked with dialing a Magnum engine, but I used to change the tip of my dial indicator to a flat tip, and place it on the top edge of the hydraulic lifter. You could also just use a solid lifter, or they make tools that slip into the bore like a lifter to make it easier to dial indicate. Goodson sells them, I believe .