Before you jump on the GV and 727, the cheaper route would be the GM 200R4. Its a 4 speed auto. Just do a quick search for Mopar To Ya theard on his install of the 200R4 into his A Body.
I did read his post when it came out, no mods to the tunnel was good. I already have the built 727 with the gear vendors and 410,s in my challenger with one of the first 360-360hp crates, ran 13.31 first and only time I took her to the track.going to put stock stuff back in challenger and use this stuff in my dart.