I run a RACOR 690T tucked up under the drivers side bed.
Fuel tank, RACOR 690T (10um), RASP, an inline ff (8um), VP44. I run Stanadyne in every tank and live in FL so do not run the heater (but good idea about triggering the RACOR heater off the OEM harness). I check my bowl weekly and drain it (never had more than a drop or two of water).
About 40k miles on the system so far. Never had a problem getting enough fuel through it.
When I change the RACOR the lp (as a RASP backup) draws the fuel through just fine. When I change the RACOR (or open the fuel system) I connect a fuel hose from the VP inlet (cap off the VP inlet so it does not lose its fuel) to the tank filler and let the lp flush the line throughly of all air and pump at full flow for a couple of cycles. Hook the VP back up and it fires right up. Oh, all fuel lines and fittings AN-6.
Hope this helps,
Bob Weis