Supplemental electric fuel pump and regulator rec's

I have a 750 cfm Street Demon carb on the ~450 HP 360 in my '70 Duster with a stock replacement Carter mechanical pump and stock 5/16" fuel line all the way from the tank pickup to the carb. Fuel supply seems marginal for my power level as after a second or 2 at WOT I can see my AFR slightly leaning out on the gauge for my wideband O2 sensor. Fuel pickup sock is good (replaced it a few years ago) and inside of tank is clean so I know it's not getting clogged. I'm thinking to keep the stock mech pump but add an electric pump that I can switch on when the carb needs extra fuel supply. What recommendations do you guys have? What electric pumps have you used that are reliable and won't be a restriction for the mech pump when not turned on?

Also my Duster is originally from California and has the Cleaner Air System with the funky vapor-capture system (pre-charcoal canister), I'm thinking to modify the extra line from the vapor capture "tube" in the trunk to the engine bay to turn it into a fuel return line so I can use a return-style regulator. I occasionally have minor issues with fuel percolation and I know using a return-type fuel system would help keep the gas going to the carb from getting too hot. So I'd also appreciate recommendations for a good return-style fuel regulator.