The TF-2 kit is intended to use on a stock transmission, using a modified governor will not be "fixed" by the kit.
If the valve body has been modified it can go in all directions, i also found out (afterwards) my valve body is actually from an earlier year 727 and had a B&M kit installed and is (still) giving me a ton of issues i am still sorting out.
Checking pressures is a must to get it right.
You can test your governor pressure with a test gauge and a micro bore hose, the pressure should match the road speed in psi and should come up as soon as you start to drive. (i.e. 10mph=10 psi, 50mph= 50 psi)
When coming to a full stop, the pressure should come back to "0".
If the car has the original governor but the tire size and/or rear end ratio has changed, things will be off and it will not shift at the right times. (i.e. my car governor pressure starts at 15mph and is too high already at this point, it shifts too early)
Shift points are a simple balancing act between your throttle pressure (engine power) and governor pressure (road speed) and are the only 2 inputs the transmission can rely on to act (shift) as required.
If the governor pressure works as described above, you need to adjust the throttle linkage.
Basically the throttle lever on the transmission has a point where it will start to increase the line pressure and a point it provides max. pressure. Note that these points are not at the start and end of the lever stroke, specially the TF-2 it will be different as they tell you to grind down the short throttle valve spool for this.
These 2 points need to match your throttle pedal idle and WOT position.
This ensures the trans gets a 100% clear signal of what you are asking for.
To get this set is a bit difficult, you will need to have the car raised off the floor for safety reasons, with the transmission in D and the brakes applied to avoid wheel rotation and the engine running at min. 1200 rpm (this to ensure the trans oil pump is delivering sufficient flow) with the transmission at operating temperature. Record the Line pressure it gives.
In this condition you need to adjust the throttle linkage so, that whenever the pedal is slightly depressed, the line pressure starts to increase straight away and reaches max. pressure at the WOT position.
(again, with the TF-2 kit i also found around a 1/4" stroke lenght of the throttle lever at the trans was still left, but the pressure did not increase during that section)
When you start playing with the 2 linkage adjustments, note down to changes you make and record the pressures, you will figure out quite fast what adjustment changes which point in the line pressure and continue adjusting it till it is right.
For checking the WOT position: make a reference point of where the upper linkage is at when at WOT so you you can remove the linkage from the carb and push it manually to that position and verify max. pressure is at that point. (or it is before or after that point, which means it needs adjustments.
If you made changes, you need to switch the car off, push the pedal to the metal and redo the reference point at WOT as it had changed after you made adjustments and verify your pressures again at the above circumstances and manually operating the throttle linkage.
And even after all this it could still shift at the wrong points, then you need to start playing with the 1-2 and 2-3 shift valve springs by installing a stiffer or lighter spring, depending the shifts are too early or late.
But setting the throttle and governor pressure as described above are the basics, if this is off you can play around and get it shifting where you want it, but it could still damage your transmission if there is not sufficient pressure.
This may cause slipping/burning the clutches and bands, harsh/soft shifts et.c
