The hardest part to keep under control for minutes at a time on 15psi is air intake temps. They get out of hand quickly as boost goes up and not being able to keep temps down can end badly. This says 2 things to me, 1. Blow through carburetor to take advantage of the latent heat of vaporization up high in the intake (that fuel injection doesn’t have) and 2. A very efficient water to air intercooler. The short block will be fine at the 7-800 level if it has good oil control and constant pressure. For some reason I like a 383 here.