[Formulajones]

Yes base pressure on the Holley should be 58 psi.

3/8 for a return line could be on the small side, depending on the size pump you are running. 3/8 would probably work up to about a 255 LPH pump, anything bigger than that I'd want to see 1/2", but I always run 1/2" anyway regardless just in case of a future pump upgrade, I don't want to have to go back and revisit it. But of course I run full length returns on my stuff. If it's a kit from Holley I would assume it's a very short return back at the fuel tank somewhere....