It was coming from the breather line that connected to the arrestors. naturally previous owner broke both nipples off of arrestors so they were just venting to bilge. Still, that was a lot of oil to be going back into the engine. Essentially, with the PCV valve, engine was only releasing blowby from the single 3/8" breather line. Now engines each a 1 qt breather can with dual 5/8" lines feeding them, no PCV. Can ports mounted well above valve covers so oil really gets a chance to fall out before it even hits the cans. I'm sure with engines being tired, the increased blowby yielded some high crankcase pressures with the tiny stock breather setup.

Thought I would chime in with an update since it was my original post. I am currently at 1050 hours on both of my 502mpi mags and they are still running strong. Nothing other than normal maintenance.