The basic function and use of hard parts still applies, but springs have been replaced with computer controlled servo's. :D
You used to be able to add half of another governor spring in with the existing spring to raise the shiftpoints across the board, but only in the higher road speeds because the first part of the travel of the governor used the resistance of the existing main spring.
Now it moves about half way easy like it did until it comes up against the extra half spring and it resists the shift longer. (basically the driveline has to spin faster for it to shift than it did before)
Any more you have to program the computers to do it. (performance chips)
I don't do any of it anymore, except my own and maybe to help here if possible.
Sometimes I run stuff by (Tracy) Fishy68 in case I miss something stupid. :D
He still does 727's.