electronic fuel pump???

With a mild build like that why not go back to a mechanical pump? Rule of thumb ... a motor uses about 1 lb/hour of fuel to make 2 hp at WOT. So for 400 hp about 200 lb/hr.
At a density of around 6.1 lb/gal that comes out to around 33 gph if my calculations are correct .... What you say - only 33 gph??? But why does everyone run these 150 - 250 GPH pumps on street cars ........? Short answer is that most pumps in use are way oversized for their application. Sure you need to factor in for a return line (if you use one), some line losses etc. But even if you sized for a a 50% return rate at WOT that is still only 50 GPH (66 GPH for 100% return - at WOT) that you need. The more the pump is oversized the more heat it generates and more power it uses to run and in general the more noise it is going to make.