I am no oil expert but Fischer Oil in Long Beach,CA Makes a "Classic" 20/50 that is popular with old car folks here in SoCal. I have used it in all my old cars for years, new engines and well worn ones.
I am sure that other, probably major companies make a zinc rich oil for the flat tappet cam engines too.
They told me that it is safer to use an oil factory blended with the zinc rather than use an additive because too much zinc is as bad as too little, also that diesel lube oil contains the good anti wear stuff too but also has a bunch of additives not necessary for gasoline engines.
562 437 6048 Ray Fischer Oil
