I sure would have been interested in that tranny with the shape mine is in. Heck we could have had a mod weekend or something and taken yours out, put in your built tranny and then pulled mine and put in your old tranny in my car.
I would personally go ahead and put in your new tranny. Your old tranny, while maybe not worth much, is worth something. I got my spare tranny off of Craigs List from a guy near OKCY that had 100k on it. I didnt really care about mileage because I knew Id be rebuilding it so it worked out great.