This is a nonissue, IMO.
I run the 402 pan and windage tray as well in my '69 Barracuda. My long block has been together for many years and still has good oil pressure. Granted it's done more sitting than rolling around town. It still runs around 35 psi hot idle 800..ish RPM.
A still @ about 1K...
I really don't know for sure as I've never actually encountered that particular situation myself. Others have mentioned and questioned the possibility. The only way to know is to open it up. If they are correct orientation, you have other issues.
Curious...Are you using a stock fuel pump...
FWIW, a 402 is a 4 qt pan and add 1 more for the filter.
Not sure you'd see any oil pressure if any oil gallery plug is missing.
One confusing item on BB's is the rocker shaft oil hole correct orientation. These oiling holes for the rockers should be pointing down and out from the bolt...
That's pretty typical for a pressed powder metal gerotor. I'm pretty sure it's not the issue as you've seen the same with a different pump.
How hot is your engine getting?
Does your oil appear frothy as in aerated?
Did the engine rebuild include listing of the clearances?
You might change your...
Intermittents are a PITA.
Basics-all grounds
Engine ground to chassis.
ECU ground to chassis
Column ground, etc..
Points (condenser failing or shorting out) or electronic ignition (loose female barrel connector in plug)?
Ballast resistor continuity and connections.
Fusible link and bulkhead...
Just throwing this out there. I haven't tried it, but how about a couple shots of 3m 77 on the carpet backing and on the corresponding deadener area where needed? Weight it down over night.
Check all you can before you install.
What's up with the crank bushing or are you running a bearing? Might be a good idea to indicate the bell in if it hasn't been. The FSM has directions. Free downloads at MyMopar.com
Unfortunately, just because "it's new" doesn't mean no issues won't arise...
Do you know if the bell housing was indicated in with all attaching bolts torqued to spec?
I've heard some clutch covers can have conflicts with bell housings. One point is mentioned in the MP bible although it's a small block comment..........
Some bell housing info here may be...
I wouldn't think the Abody rods to be the same length as the Ebody due to the shift adapter bosses on the trans are further back.
However, there's this for the VGII....
https://www.shifterdoc.com/Hurst_3738180_Installation_Instuctions.PDF
1 (minimum) to 1-1/2 times the bolt diameter protrusion is typical.
Should not take that long.
What does your mechanical oil pressure gauge read with the prime?