WANTED: Slant six Holley 1 brl carb (Preferably 1920 model)

Was that off of an early or late A?
Dartsun can answer exactly, but I'll jump in and say that a cable-operated slant carb should be 1966+, but there were other varieties for later emissions, like the bowl vent tube, extra vacuum ports, etc. Generally, you can use a later carb by blocking off unneeded ports, but not vice-versa.

Of course, those w/ 1965- cars, a rotating rod throttle input is factory. But, one can install a throttle cable in 1964-65 cars since the V-8 cars used that, but would need the now-rare pedal and cable assembly. I saw a 1963 Dart in the junkyard w/ a throttle and cable from something much later (1990's?) cobbled in. There is also Lokar after-market.