Sorry to sound so curt with you. Click on the following link if you want to see a thread I started on Auto Restorer On-Line about some more efficient ways to get older engines to run on pump gas. If you scroll down, look for threads that are about shimming heads, or just do a search for my name.
Never mind, looks like that thread was archived or something. Anyway, the gist of it was that you could pay a machine shop to install hardened valve seats, or you could go to a place like Summit and for just a little more money get a new set of heads with larger valves and better flow, with the seats already installed. FWIW I did a frame-off on a '67 IH Scout 800 and to have a machine shop rebuild just one head (deck it, new valves, springs, and seals, already had hardened seats) was $330. A new set of 390 heads runs around $800 unless you really go gonzo.
As far as running on pump gas, the guys on the other forum said they only add lead very rarely, as opposed to each gas tank. One guy said he only adds it when he first buys the car, then never again. That seems a bit extreme to me. I do it once a month or so. For the higher-compression engines that run premium, what they said to do was just run it on cheap gas, and if it starts knocking retard the timing. If you have to retard the timing too much, you can add a second, high-quality head gasket to "shim" the head up and lower your compression ratio slightly. Most guys have said they've had no problems just playing with timing, but if you have to shim it make sure you use a really good gasket, since they're not really designed to work that way.
Darel
