Joe H,
Let me drop 2 small corrections to your information. The 230,250,292s are the same length to a small amount shorter than the 235 and 261. See Leo Santucci's book on the bottom of page 2. Also, most if not all TF up trucks with the 235 or 261 used side mounts that were almost to the front of the block.
During TF production, Chevrolet used 2 different bell housings, (with many different casting numbers,) in the 3 speed manual trucks.
One fit the 235/261, and the other fit all the V-8s. As long as the bell housing bolts to a V-8 and has provision for mounts, it
will work.
BTW, my Chevy book shows a 1970 250 L6 as having 155hp and 235 ft lbs of torque @ 1600rpm. Not to bad. A 1968 is probably about the same.
