Thanks for the suggestions guys. Sorry I haven't replied until now but, right after I posted the initial question, my company sent me out of town on business and I just got back. My existing setup is two Stewart-Warner fuel pumps mounted in the trunk, similar to the original 427SC. The location is less than ideal and on hot days they can cavitate. I've decided to go with a single Mallory fuel pump mounted below the tank level, where it should be (I'll leave the SW's in the trunk for appearance sake). I like the design of the Mallory, I believe it uses a gear rotor design similar to an
oil pump as opposed to the rotary vane design used by most others, including the Holley. I'll use the Mallory bypass regulator as well. Ordered them today from Jegs. I may try to find a way to plumb in the SW's in parallel so they could be used in case the Mallory pump ever quits (what can I say, I'm a belt
and suspenders kind of guy).
On the return tube I'm adding to the tank, I've decided to 1) extend the tube to the bottom of the tank 2) aim the fuel away from the pickup and towards a bulkhead and 3) drill a 1/16th inch pinhole in the return tube just inside the tank wall as an air bleed hole so that I can disconnect a line upstream if I have to without worrying about siphoning the tank contents out on the garage floor.
Think this setup will work? If I put the existing pumps in parallel as a backup system, should I isolate them with a checkvalve or a manually operated ball valve?
Steve