oil pouring through rear main seal

[MidLifer]

I recently got done with putting a LQ4 into my 71. When it first started up, it started pouring oil out the rear main seal. Figuring it was rear cover alignment, I bought the AlignIt tool from Sac City Corvette, followed the instructions and replaced the seal. Leaked again. Removed PCV hoses, oil cap and dipstick, no change.

I did the whole procedure one more time, making sure the crank was clean and dry and I was putting the seal in the right way (being able to see "this side out"). Even put a dial gauge on the crank to see if it might be bent, only saw 1/1000 of runout. Stuck a micrometer between the cover and the crank after installing the cover and measured less than 2/1000s of difference all the way around.

Same leak happened when I started up the engine.

It does not look like it is leaking through any of the cover bolts. When I look behind the flexplate I see the oil coming out from the bottom of the rear main.

I've read every thread I can find here and on other sites about this issue. I would suspect crankcase pressure, but wouldn't taking the oil cap off relieve that? Also I did not feel any air coming out the filler hole with the engine running.

I'm not using a turbo, this is a stock engine.

What should I try next?