My 71 Dart is a turd until a minimum 1500 RPM. Stock 340 and 3.23 rear gears. But I think my converter stalls at less than 2000 RPM so the converter is the first thing to address. Gears will stay due to the amount of highway miles it sees.
Stock 340 verter stalls over 2k
anything under 2k doesnt even matter
tune the setup
my 340 268 650 dp 3.23s dead stop punch from 850 rpm smokes the tires instantly tach jumps to 5500 stays there then 15 feet on the 1 to 2 shift at 50ish mph if i so choose
now 3.91s will smoke 1st and 2nd 5800 rpm if i want