Well, I got news on the head today. The shop will be drilling out the guides and installing oversize valves, milling, and pulling the exhaust bolts. On this "original" engine, the only visible change will be the later-style exhaust manifold. Not only will it breathe better, but I've found it nearly impossible to find the old style WITH the hot air choke tube hole (only on Comets, not Falcons). If anyone knows of a good one around, let me know, but most end up broken anyway. Mine had two bolt ears cracked off, and it was pampered most of its life.