I managed to obtain a 727 transmission. I am going to pick up a 727 street rebuild kit from Cope Racing Transmissions and get it rebuilt. I plan on putting it in the car myself.
You'll have to flatten the pinchweld at the lower firewall/floor in order to make the 727 fit. A 904 can be built to take whatever you throw at it and fits without modding the pinchweld - just saying.
When I lived in Annandale, I used to visit B & B every couple of months, just to go through the Mopar section and see what treasures I could find - like an 8.75 in a 65 Dart. Haven't been there in years though.