Oil Pan leaking, one side only!!!

Just put together a 360 Magnum and I completed a run down on my Jed Clampett Run Stand!!!

Everything is great with the exception of my oil pan is leaking while it’s running on one side only.

360 with a windage tray for a 360 (holes are slotted)

I put 5 qts of oil and one bottle of STP Oil treatment w/Zink (15oz)

At first I thought it was crankcase pressure buildup but, I do have the PVC connected and it’s still leaking.

I even pulled the dipstick out to see if that would help elevate the issue, it did help some but not much.

The Oil Pan was used when I got it and I checked it for war page and found no issues that I could see. I did mod the corners where it meets the timing cover as Magnums are different and no issues there, it all on the passenger side as you can see in the photos.

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What is this? Magnum engine, LA timing cover, and LA oil pan?
What style oil pan gasket was used; LA with cork side rails that squish out easily and leak if RTV is smeared on them and they are quickly tightened?
Any chance the oil filter adapter plate is leaking? Is it an LA plate on a Magnum, which is said to leak badly?
Did the oil pan rail sit flat against the block with NO oil pan gasket installed, during mockup?