Highest Lower Stack Height on a threaded headset?
 

Is there one that is greater than 19mm for a 1981 road bike?

Must it be the bottom section that adds all the required stack height? Stack under the head tube make a very tiny change to the various angles but it can't be much. (And I really don't feel like calculating them now. Maybe after I've posted this note...) You can increase stack height by adding spacers between the upper race and the locknut on the top. Velo Orange has them. Or at least they used to.

I doubt it. The standard Tange headset is about 10 1/2 mm - so you're talking almost twice that height.

Shorten fork? Cut more threads first, if necessary.

I have seen some listings on the internet last year, but cannot seem to find then now.