Trans shift points?

Wondering if there’s a way to adjust my shift points.... I’ve got a 74 Duster I dropped in a 340 and a new 727...aftermarket everything. Running a lokar lockdown and a quickfuel carb. Car runs and drives great, but shifts early and I wish it would kick down a little quicker. Was wondering if this is in the cable adjustment? As is, it has about 1/16” slack with no throttle.