ring/pinion swap in 7 1/4 for lower gears?

Here's the situation:

1963 Dart GT 225 /6 with a 1972 A-833 close-ratio box installed in the distant past (no history)

Rear axle replaced with a big bolt pattern 7 1/4 from an auto '75 Dart; 2.76 gears


Result: feels like launching in second gear! Have to slip the clutch, barely get out of first in the city and bogs badly.

I do have a small bolt pattern 7 1/4 axle with 3.23 (approx) gears sitting on the garage floor.


The question: Can I swap the SBP 3.23 gears into the BBP 2.76 housing? If they fit, how much work is setting up a ring and pinion? I wish I could just swap axle shafts/hubs but I understand that the BBP and SBP hubs are not interchangeable.

I guess the ultimate solution is a BBP 8 1/4 with 3.23 gears; I'd settle for a BBP 7 1/4 3.23 as well, but just not finding anything available in the San Francisco Bay Area...

Thanks in advance!

Marc