Newbie with 360 LA problem

It has Mopar cast aluminum valve covers that have been drilled out to accept Billet Specialties breather and PCV. The engine idles and runs smoothly with no weirdness. I have a hard time believing it's pulling a vacuum on the crankcase when that breather is unrestricted, no matter what may be happening with the PCV.

This has the front seal with lips on both sides of the flange. The last one was glued to the flange...and no, this is not the wrong pan. I've built many engines from Porsche to Pontiac to ABC. This is my first Mopar but it isn't my first engine build. Something is definitely weird here, however.