doing a 495 out of a 455 pontiac right know . a 455 is not the same in any way to bbc so you need to buy a trans adapter plate or a chevy 400 trans to bolt to the chevy bolt pattern. dimple rods do not mean much they do not add power the engine will not care same with what the pistons or crank are made of only when you add power adders and RPMs . the mark 5 dimple rods are not better then the old truck or thumb rods hard to say what you have for a engine before you can say what your going to get for hp realistic would be 400 hp no machine work ? need a hell of lot more info on the engine. i am thinking you trying to do this on the cheap? seldom do big HP numbers and cheap go hand in hand