You can get real close with a cam as small as a comp xe268H or Voodoo 268 as long as the heads flow well in the lift range.

If you have some time to run a grinder, there are a bunch of articles, how to, on getting J heads in shape to flow 240+ at .500 lift. That's enough air from the heads to make 400 hp without going crazy on a cam, losing drivability.

An Air gap, RPM performer or LD340 would be good for an intake. Opening up the port window on the Action Plus would be a good start with a grinder. I'd look for the ede intakes. Sell the action + for funds.

Quench with a zero deck flat top piston and J heads? Good luck with that!