There is so much bad data on the clutch fork. And some of it comes from previous posts here.
The biggest issue is that 60-68 MPC lists a C7ZZ-7515-D for the 67 F(Special).
This fork is 12" long. I bought it based on multiple recommendations, including the one from the vendor who sold it to me -- based on the MPC.
I also have a C5OE-7515-B. This is the snake tongue version many say is a service replacement. It was on my car (untouched for over 35 years) and on a friends car that predates that date by another dozen years. But the validity of the C5OE-B is not the question. It's the 12" long C7ZZ-D. (I believe this to be a C2 big block fork) The C3 is almost the same and I can't differentiate via pictures).
I took out a previously running 66 289 and mounted the following parts on that:
-Left and right C3/C4 Hipo exhaust manifolds
-10.5 Clutch left in place
-Correct 67 bellhousing
-Correct for 67 HiPo (See Gregory's book pg 67) Z bar
-New, SD Exhaust H pipe
-An 8 1/4" threaded rod to replace the push rod which I can't find at the moment
-Threaded stud block for push rod
-Two forks -- the 12" and the snake tongue.
That setup is in the pictures.
Pic 1-- The 60-68 MPC
Pic 2-- The rig
Pic 3-- View of how the Z-bar was fitted and how the snake tongue fork aligns with the push rod. I have other views of this including the horizontal as viewed from the frame rail.
Pic 4 -- View of the direction the push rod goes with 12" installed
Pic 5 -- Pic of how the threaded stud block looks with 12" installed
Pic 6 -- H pipe removed showing the extreme angle of the 12".
Pic 7 -- 12" on top and various 65-67 289 clutch forks underneath
So, the MPC is wrong. The 12" simply cannot work. However I have yet to see a pic of an unmolested, original fork on an original car in order to settle on what the end looks like.