With a 240 iron head, our cnc has a program to begin port work. It's a 3 axis so you gotta finish by hand. We built a 300 with this head after spending hours doing port work and it made 412 horse. It was a drag motor with aluminum rods and a big cam. About 13:1 compression. I've worked on the EFI heads with the slightly better chamber but only about a gasket match. Good valve job and some bowl work. Made just over 300. Roughly stock compression for the EFI. I know with an aluminum head with a good chamber and revised ports we could hit 400+ on pump gas and a streetable cam. Let alone what could be done with boost.