i don't disagree with your reference to TQ being made by the stroke. but on top of that, if your gonna go RB, all strokes being equal, the extra displacement can help out. chances are its gonna have to be bored during the rebuild anyway, might as well go to a stock size. a good low rise dual plane, the proper carb and jetting and a cam made for low end will do the trick. regardless of what Rb is gonna be used, making peak TQ at around 2000rpm is gonna be tough. all your specs are off the stock factory set up im assuming, and cam/intake technology has come a loooong way since those were made. to further my argument, the 440 with a much bigger bore makes more TQ at a lower rpm then the 426/413, is it because that's where they tested it, is it cam and intake choice?? who knows but it does help to argue your "smaller bore is better" theory. you want the TQ curve to start low as possible, and ideal situation peak about 2000-2500rpm. pretty easy to do with whats out there now. use my 455 for example, bore is 4.3125, stroke is 3.90 and she makes 510lbft of TQ at 2600rpm (straight from the factory). but thats peak tq, she is still making over 300tq around 1500rpm. displacement does help :0)