273 Supercharged...ITS HAPPENING PEOPLE!!

Have a look at this thread and see Bill Dedman's post where he talks about what he learned from a guy who has a lot of Torqueflite experience - 273's tend to wind high, so, that bit about 'above 6000 RPM' may be relevant to your build:

http://www.forabodiesonly.com/mopar/archive/index.php/t-50518.html

Also, this thread is interesting:

http://www.forabodiesonly.com/mopar/archive/index.php/t-288545.html

These threads hold a lot of cool information. Long reads but good info. Being a full on full interior street car my trans choice was all about cost up front. The 904 was going to be more money even though I had the core. So I went 727. I still have the 904 and I'm not selling it. So maybe I will slowly build it myself after all is said and done. But for now I have a lot going on at work, 3 kids and I am staring at a huge build just to get this thing running and driving. So adding a trans build is not in the cards.