I shortened mine somewhat like this, however it was removed from the car. The joint that is heated is made with something like 3M 5200 polyurethane sealer (for boats) that gives a good bond yet gives additional viboration isolation. I thought the rod by itself would be a little too short, so I cut down the black shaft about 1 1/4" and re-attached the threaded portion by drilling 2 holes through the whole works and used the mandrel from a stainless pop rivet for a pin and peened the ends, that way you can still use threaded knobs. I also ran a dye nut down the thread to allow the knob to screw down a little lower.
I had a TWM but got tired of the effort required and put the stocker back in after modifying it. I also have the kartboy bushing and this helps a great deal.
I tried to modify my twm by cutting, shortening and rewelding it back together to lengthen the throw/lower the effort somewhat between stock and original, but the weldor didn't use enough heat and the weld failed when I tried a little NDT in the bench vise. Not entirely his fault as I was trying not to remove the bearings.
All in all, I'm pretty happy with shortening just the top half of the stock shifter combined with the KB bushing. I also made a new leather boot and ended up with a MOMO leather knob, so it looks stock.
Rusty in San Diego