Very interesting thread. I'm going to have to watch this one. I have less cubes, less weight, less cam, but a 4-speed and a 3.54 gear. I was going to put a 30" tall tire on it, but this is making me think twice. Unless I go to a 4.10 or a 4.30. I think I can live with the RPM at 75 MPH with either gear and the tall tire.
Good luck. I hope you can hit your goal. If you have one.

1969 Dart GTS 340
1969 Super Bee X9 N-96
1969 Coronet R/T X9 N-96
2015 Dodge Dart GT
2019 Ram 2500 Big Horn.
Looking for the original block for my Bee. The last 4 are 7449