The only way to get 340 cubes out of a teener at 3.94 bore is to use a 3.48 stroke.
For reference;
My Zero-deck 360, with alloy heads, and running the pressure up into the zone of 185>195 psi, makes more torque than my 68 Barracuda chassis can handle, but
it will burn 87E10, at full-timing...