273 vs 318

Once driving a hi-po with a 4 speed, in my former 67 notch back, these motors rev fast and high. Like previously discussed, this is not a standard motor. Aluminum pistons, high lift cam, dual point ignition. Very unique sound with the dual point distributor. However, the heads are it's limitation, so 650 cfm is the max carb to use. There are (2) 318 heads with hardened seats that will work on these with bigger valves. Do not remember which ones. Need to be careful of the valve to head face interference. With the smaller bore, the head needs to have the valves inside the combustion chamber.