Turbo....

One thing that might be in your slanty's favor, is the actual Force on the top of that 3.4xx" piston when the ignition fires. Whatever psi is there, the actual force would only be 85% of what it would be on a 4incher.

Assuming identical pressure, the resulting force from a 3.4 bore is 72% of a 4.0 bore.
pi x radius squared