430+hp 340 possibilities

My '70 340 on the chassis dyno made 279HP to the tire: 20% more is 330 at the flywheel. Exactly 100 shy of your goal. Now, where can that much power be found? This engine had factory pistons, crank, rods. New rings / bearings and the heads are factory J heads with minor bowl blending, the cam was a Hyd Roller that peaked at 5700rpm. This combination used an RPM intake, a 750 Holley, had headers, and 2 1/2 exhaust.

Pistons- upgraded both in weight and compression height as well as a slight dome could be a solid improvement. I would venture to say 35hp could be found there.

Head flow- Going far past where I stopped that go around would be necessary, upgraded valves and springs capable of the RPM to push past where mine nosed over. If you are really make the effort to neckdown the guide boss, open the pinch and the bowl up as well as mill the heads considerably another 35hp if not more depending on execution.

STILL... we are in the hunt for 30 more! This is where a better cam than I had is key and RPM is going to be desired past where mine was limited. No matter if you go FLAT or Roller; Solid be your easiest route to achieve that 430 number!

There is nickel and dime items here and there to pad the stats like carburetor, intake porting, valvetrain upgrades, balance/lightening, exhaust, tune and ignition. But for a factory stroke 340 and factory heads 430 is achievable but you are gonna have to want it and get it right! I hope this helps you in your approach to your admirable goal of not taking the easy button; Which is a 408 or a Gen III Hemi.