What head should I get for a 318

Gears are 3.91s with a 2.74 first gear and 1.54 second with a 27" tall tire. Thats what I am thinking, keep the motor cool-I always run a 160 T S in the summer and a 180 this time of year. Rad. in great shape with a electriac fan which I only need when its more than 70 degrees. I call my local junk yard today and they have them for $75 a peice. First place I called had them, might get 3 heads and keep one-unwork-as a spare. Like the compression going up and the bigger valves should help the flow. Not sure if it give me more rpms but it can turn 5700 right now. The adjustables rockers gave me 300 rpms more-must have had to much pre-load on the lifters I guess.