Nothing that can't be done with the older stuff if your willing to start over and use EFI in the process.

Better flowing heads
Higher Static Compression
EFI
Better Cam Profiles
RPMs

All the same stuff that the imports have been doing for years Making 1.0-4.0L 4&6 bangers that fly and sip on gas doing it.

Those 5 are your primary factors. Several others as well but to a lesser extent.

Far as Racing them. Call Ray Barton and ask him. His brother is flying in Stock Class Racing.