To use a mechanical clutch linkage with a big block will require a lot of fabrication and trial and error. The exhaust manifolds are in the way and the big block ball stud mount is not in the correct location. Here is the for sale thread for my '63-'66 booster bracket with the hydraulic clutch conversion.
http://www.67-72chevytrucks.com/vboa...d.php?t=651200