Ford did away with the Dual Range feature beginning in '67, which made the C4 easier to understand. Along with a new name for '67-Select-Shift-the later version switched to the more normal P-R-N-D-2-1 pattern.
The kick-down linkage, vacuum modulator, and output shaft governor work together to control upshift and downshift points. Throttle position is what controls both kick-down and vacuum modulation, a fancy term for the amount of intake manifold vacuum and its effect on transmission upshift timing. When there's more throttle, we have less manifold vacuum. When your foot is off the gas, we have high manifold vacuum. The kick-down cable is strictly for aggressive acceleration where a downshift is needed into what many people call "passing gear" (actually Second or First gear, depending on vehicle speed).
Under normal acceleration, 1-2 upshifts in Drive should happen at 17-30 mph; 2-3 upshifts should occur at 32-50 mph.
During deceleration, 3-2 downshift should happen at 33-37 mph, then 2-1 downshift at 19-21 mph. These are broad speed ranges based on the Ford Shop Manual, along with tire size and axle ratio.
At wide-open throttle, 1-2 upshift should occur at 27-41 mph, then 2-3 upshift at 52-74 mph, again based on the Ford Shop Manual, tire size, and axle ratio.