The only function the cable serves on a 350 is for kickdown. It will shift up and down correctly without any problems with the cable disconnected. If you simply must have a forced downshift, rig a cable setup that gets pulled tight just as full throttle is reached, or use a push button switch on the shift handle and a starter solenoid to yank the cable.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!