7174duster, you'll probably be happier keeping the 318 heads on there. As Bobby mentioned, with the 360 heads you'll loose some compression ratio and you'll also loose velocity in the heads due to the larger ports and valves. Basically what this means in every day driving is that it will loose a lot of snap on the bottom end, and that's where you need it for the street. If you're planning to build a 360 anyway, keep your present 318 combo until the 360 is ready. Then you'll see some real horsepower and torque increases over the 318. Good luck.