Kickdown system education needed

[PbFut]

After 50+ years of hot rodding, this is my first automatic transmission I’ve owned. After doing some research I am not 100% sure on a few details of the TH350 kickdown system. As I understand it, there are 2 switches, so to speak, that will drop the transmission down from drive to 2nd. One is the vacuum module that, as I understand, limits the line pressure in the transmission to delay shifting further up the RPM range or down shifting when a low vacuum state is achieved under heavy engine load. I am guessing there is some sort of mechanical weight governor as well to work in conjunction with the vacuum module. The kickdown cable is a little less clear to me. Does the cable modify the vacuum signal which in turn affects line pressure and ultimately shifting? Or, is there a second valve in the pressure line adjusted by the kickdown cable directly. Is this kickdown cable system variable or like an on off switch closing a valve at the last bit of throttle travel?
The modifications I am currently in the middle of will need to eliminate the kickdown cable. Can I use a micro switch to trigger a solenoid activated vacuum valve to close the vacuum line to the module and get the same down shift result? Is this how a TH400 works, given there is an electrical switch involved with that transmission?

[Rust_never_sleeps]

TH350 actuates a valve directly.
IIRC, 400 is also valved, but a switch on the carb triggers a solenoid to open it https://www.onallcylinders.com/2014/...like-3-speeds/

I Stole this snippet from Ken Ruggles' book, (which has a whole section on performance mods, but I ain't never done that):

[PbFut]

got it. Thanks Rust. So now I need to engineer a solenoid setup that will pull the cable at WOT. Anyone know of a kit?

[Accelo]

The THM350 only requires a cable and bracket to be functional. Nothing electrical.
You can run without it but it will lack the crisp down-shift it will have with it working.

The 700R4/4L60 has a TV cable and has to have it connected and functioning or it will immediately trash the transmission.

The 700R4/4L60 has a TV cable looks like and connected the same as the kick-down cable but the function is completely different.

Unless. by chance, you have a THM350C with the lock-up converter and you want that to function. It is electrically powered.