The statement above, that 20% of the gas sold in the U.S. is leaded is B.S....at least B.S. from a practical standpoint.
It may be "legal" to sell leaded gasoline but....EPA severely regulates the amount of lead in gasoline and it's so small that the gasoline is truly unleaded. The only leaded gasoline dispensed into vehicles today is AVGAS and even that is "low lead" and it only can be dispensed into a fuel tank of an airplane or into a container which the vendor knows is going to be used to pour fuel into an airplane. The only other leaded gas sold is racing gasoline and is not for use in road vehicles.
It is true that tetraethyl lead (TEL) is highly toxic. It is absorbed through the skin and causes illness or death. While you may find products which claim to contain TEL, the amount of tetraethyl lead is so small, that it is of dubious effectiveness in making a practical increase in the octane of gasoline.
If Jack Podel is selling some TEL additive which he claims you can pour it in the tank of a C1-C3 equipped with a high-compression, high-performance or special-high-performance engine, then run the typical 91-oct pump gas, he's out of touch with reality.
I've done a fair amount of testing of gasolines (see
http://www.idavette.net/hib/fuel/index.htm) and no pour-in octane booster can be that effective, other than the few of them which use the active ingrediant "MMT". Unfortunately, once you put enough MMT in a booster and use enough of that booster to raise the R+M/2 octane to 95 or 96 you bring a host of other problems to your engine.
There are no free lunches. To run a pre-1970 11:1 motor on the street, today, and drive it aggressively you need 1) have hard valve seats in the heads and use enough unleaded racing gas to get you up to 96 oct (R+M/2) or 2) start mixing unleaded pump gas with leaded racing gas.
Octane boosters won't do it...at least not safely and practically.
Retarded timing won't do it, either.
Lastly, this problem is related to compression ratio and spark timing, NOT the existence of Rochester Fuel Injection. High-compression, four-barrel engines have the same problem.