You fellows should remember though, that before about 1972, we had tetraethyl lead in our fuel that would work with the valve seats of the day. If you resurrect one of these motors today, you must cut and install hard exhaust seats to prevent recession of the valve down into the head.
Now, I know that a few fellows will come on and tell us how they have been runnin' unleaded gas on early heads with no problem. BULL HOCKEY!!!! If you're gonna run pre-'72 heads with unleaded fuel, you're asking for trouble if you don't install hard seats.
Some of you fellows may be able to pick up a few pointers by reading through these articles. Joe Mondello was one of the premier Olds afficionados until his recent passing, but it is my understanding that his son, Bernard has taken the reins and is continuing the business.
A friend of mine, Bob Parmenter, schooled me on the valve recession nightmare and why tetraethyl lead worked. It seems that without lead, every time the valve closes, it micro-welds a tiny little bit of the valve to the seat. Next time the valve opens, it rips off the tiny bit of seat that was welded to the valve. After doing this enough times, you can see that the valve would work its way down into the head. Now, in the same way that you cannot weld a dirty connection, the tetraethyl lead coated the valve and seat and acted as a dirtying agent, preventing welding at the valve/seat interface. Cool beans, Huh?