Fuel system Help!

[65_LS1_T56]

Ok, I'm in trouble. I need some expertise in fuel system setup here. I've lost two Holley 12-700 billet pumps in 130 miles. First some details on the car.
-65 Chevelle
-98 LS1 mild rebuild, small cam, 36# injectors, stock fuel rail (returnless style), shorty headers, estimating 400 FWHP
-Holley HP efi ecm
-Early (earlier, not sure when it was made) Ricks SS tank
-Holley 12-700 inline billet pump (intank)
-Holley 100 micron pre filter (intank)
-Holley regulator, mounted on outside of tank, return plumbed back to tank set at 44psi
-6 AN flex line from regulator to chassis (~18")
-3/8 hard stainless to firewall, 10 micron inline filter half way
-6AN flex line from chassis to fuel rail (~24")
-Holley 100psi pressure sensor mounted where Schrader valve was in fuel rail
-Electrical: HP efi fuel pump output goes to a standard (mechanical switching) relay. That relay switches a ground that is passed to a solid state relay that switches the power to the fuel pump. The solid state relay was used as I plan on using the PWM output function of the HP efi someday. (could there be something here causing a problem??)

Anybody use the "bulkhead" electrical pass thru like this? Seems odd having exposed electrical connectors submersed in fuel??

Some pictures, on the bench building it, shows regulator mounting:

view in tank. On the right side is a "U" tube (pump to prefilter), On the left is a pickup tube that goes thru a baffle wall in the tank. The return line also dumps the unused fuel in this baffled area (cavitation problem??)

I can get more pictures if anyone has any ideas...I'm not going to throw another $250 pump at it, I need to find the problem. I need some help here guys, I'm beside myself couldn't sleep last night. One week to Motorstate so I have to get this licked.

Thanks in advance for any suggestions or comments