the heads are stock 67-71 327&350, don't know about combustion chamber cc's, Mortec has no info for that on these heads. The torker 2 is a single plain, not great for off idle performance like a dual plain, they like a fair amount of compression also, and run from 2,500 RPM. Get a Performer manifold, headders, light cam, a smaller carb, Holley 650 vac secondaries or somthing like that.