From my experience, you want the biggest bore, and still keep the cylinder walls thick enough they do not flex, you don't make any power if the rings don't stay sealed under power. And on the dyno testing, just keeping track of the engines I dynoed, the peak numbers may be close, but those that I did the average HP numbers were always higher on the big bore engines, and higher average numbers usually will out run higher peak numbers given the same chassis combination. The best example was to 383 small block chey's I built for mud jeeps. One was a 350 block stroked, the other was a 400 de-stroked. The 350 had some better heads, and made about 20HP more, but the 400 had better average numbers, in the mud pit, the 400 jeep smoked the 350 block.