My engine set-up is very similar to yours, except I have a Dominator. I use a mechanical pump backed up by a Holley gerotor electric.
The mechanical does just fine for the majority of the street time. I have the electric mounted on a strip of old used tire that is attached to the upper shock cross member. The electric is controlled by a micro switch actuated by the secondary accelerator pump arm. I also have a manual switch under the dash just in case something happens.
This combo has served me well for several years now and will feed the Cuda into the 6s @ 104 in the 1/8. Its quiet, dependable, and affordable.
3/8" hard line would starve the engine occasionally when the car was warm. 1/2" was just about impossible to run. So I ran 3/8" hose and bored out the fittings as much as possible. That fixed the delivery problem.
I run about 5.5lbs of regulated fuel pressure. I do not have a return line, but if I ever have to change the fuel delivery set-up, I will add one and change to the appropriate regulator.
IMHO you do not have to spend a thousand dollars or so to feed a stout 500" engine.