Hi Turk,
have you considered the T56 6 speed? With a 2.66 or 2.97 first gear it's a bit more useful than the tremec TKO. The 0.5 or 0.62 ratio 6th you would get some pretty good gas milage out of that 427. It has the same torque rating and uses the same input/output shaft splines as the TKO.
Salee Chevrolet sells one that bolts up to a standard patern bellhousing so it would be easy to adapt up. Plus with your GM connections you should be able to get one at the right price.
http://www.sallee-chevrolet.com/BorgWarner/t56pics.html
The numbers for a 3.45 rear end look pretty good with this box. Your B/B with it's superior low down torque would be better than my LS1 at 3.45. I plan on going to 3.9
I can machine up a nice Alloy knob for you as well.
Cheers