Post up the outcome when you get it done. I am putting a TH400 in place of I believe the car came with a TH350. I purchased the 400 front yoke from a Camaro parts catalog and haven't had the chance to look and see if the shaft is going to need to be shortened or not.
1969 350HO, 60.000 orig miles http://www.allaboutspeed.com BB dedicated to all forms of cars restoration and performance.