[lust4speed]

I'd bet that either set of heads would currently measure out to about 78cc's, and will be at 75cc's after a cleanup cut. You will have too much compression on a 400 (probably an honest 9.8:1 after the heads are done) to run the 2801 cam. Both heads have small valves and pressed in rocker studs. The pressed in studs would be iffy with the duration and lift of the 2802 cam.

You're between a rock and a hard place with your current heads. When you start paying a machine shop for the labor and materials to bring a set of heads up to par, the heads themselves become the cheapest part of the operation. I'd start with a set of heads that already had the large valves and screw in studs, and I would also choose a head with a large chamber that could be milled down to achieve between 82 to 84cc's to keep the compression ratio at 9.3:1 or a little below. Then all you have to do is select the proper springs and installed height to keep the 2802's .488" lift away from coil bind. Replacing all the valves is also a must. Way too many engines have been destroyed with the false economy of keeping the original 2-piece valves. While they seem to last forever in a stock engine, increasing spring pressure and kicking up the valve action all too often has the valve heads breaking off and causing cataclysmic destruction.