Someone disagreed with my post. I have thick skin, and the fact that someone disagreed with me does not bother me, I am just curious as to what part of the post he disagreed with. Does he think 325 HP is not doable? Or does he disagree with my comment that sticking with his current motor (if possible) would simplify everything. Many years ago, either Car Craft or Hot Rod magazine had a HP contest for 3 small block motors. They started with a 350 Chevy, a 351 Windsor and a 318. They set a budget of about $1500, and the 318 made the most power (about 340 or so if I remember). So I guess it boils down to what the OP wants. If he wants a nice cruiser with a nice V8 that will smoke the tires, a 318 will do it. But if he wants to go racing and eventually pump the motor up to 450 - 500 HP some day, then go with more displacement. But to disagree with the fact that a 318 can easily put out 325 HP (with the right parts) and that sticking with your current motor (and not having to worry about changing anything) will be easier in the long run does not make a lot of sense.
