the neutral saftey switch and reverse switch should be at the base of the steering column. i s'pose the th350 may have a reverse switch on the trans itself for different applications.
the cable should be setup the same as the TV cables in later transmissions, which can be changed out without dropping the pan. there is a hook which comes up from the trans and fits into an eylet on the base of the cable. undo the bolt which holds the cable, and pull it up 'till you feel it stop, then hold the hook up with a pocket screwdriver, and slide the eylet of the old cable off, and the new one on. if by some chance the hook falls in, which it should not be able to, or you have any major problems, such as a bent hook, or there's not enough room to get the cable off, it can be done with the pan off.
you will probably want to scour a salvage yard for a bracket, or make one. as far as hooking it to the carb correctly, it will be about 180* out from where the accelerator hooks to it, as it will be going in the opposite direction ( it is pulled toward the front, while the gas cable pulls rearward) there may be kits for this thru art carr or similar sources if your carb has no place for it. the cable needs to be relaxed at idle, and fully pulled to the stop in the trans. at WOT. hope this helps.
