470 all the way. Low compression 8:1 ish. Pump gas is only a problem if you aren’t intercooled, have poor timing controls, and/or poor mixtures.
A fraction of the money saved on the block should go to an efi system with COP capabilities. 18 psi is easily doable with precise fuel/ timing controls.
If you run a distributor / carb you will fail.
I used billet steel bbc rods in mine from Crower.

"use it 'till it breaks, replace as needed"