Power advantage between Ford 351, Mopar 340 and Chevy 350??

If you are talking on the late 60's early 70's engines with stock cast iron heads, the 351 Cleveland with 4V heads can make more power that the Mopar 340 or the Chevy 350 just because of the amount of airlfow through the heads. Same as the Mopar 340 should make more power than the double hump 350 as the heads flow a bit better. If you are talking about the 351 Windsor it would probably be at the bottom of the pile as the cast iron 351 W heads do not flow very well.

It seems that your question is more along the lines of the bore/stroke combination of the engines, rod to stroke ratios, and what difference that will make. As if everything else if basically the same, with head airflow, intakes, carb sizes, headers etc... the only real differences would be the basic architecture of the engines. The bore and stokes are very similar, Chevy 350 and Ford 351 (both C and W) have a 4 inch bore, and the 340 has a 4.04 bore, the Chevy has a 3.48 inch stroke, the Ford a 3.5 and the Mopar 340 a 3.31 (360 has 3.58). The best rod to stroke ratio would be had by the 340, but not by much, the 351 W would be right behind and the 350 Chevy and 351 C would pick up the rear. Having said that the difference is minor, so I doubt it would really make much of a difference. If these engines were built to the same specs as you suggest, they would all make really close to the same power. I would bet the whichever engine had more displacement would probably make more power and torque, so a 360 Mopar would probably make a little more power than a 350 or a 351 and certainly more than a 340. Now, if the displacements were the same, I bet the power difference would be almost nothing. After all an engine is just an air pump, if the amount of air coming in and going out of these engines is basically identical (as per the head flow, cams, carbs, and everything else being the same) they should make, at the same displacement, about the same amount of power. The differences in bore sizes and rod/stroke ratios are not enough to really make a big difference.