418 Stroker options....

With a stroker kit in the 340 to displace 418, making 500 hp just got a bit easier and it is easy to make that kind of power. You'll only need to make 1.19 hp per cube to get 500hp.
At 1.43 hp per cube in a 418 is 600hp. That's still not a lot of power per cube. It approaches what I think, IMO, is a typical well built hot street car.

When you start to exceed the 1.5 hp per cube, your starting to cook. At 1.7 per cube, the 418 is just over 700hp. A whooping .2 jump in power per cube.


Heads are the next key to the combo.

Now the question is are you going to pressurize the engine or not? And do you want a hair drier or through the hood roots style?

Oh, do not be afraid to sleeve the cylinder. So long as the shop can ha doe the job and do it right, you'll be fine. FWIW, a .060 slug is easier to get sometimes than a .040 slug

Switching to a big block is your call. But you can do the math with the new cube size.
500 X's 1.5 = 750hp
500 X's 1.7 = 850hp

The stock trans will not hold.