I would seriously consider using a 4L80e based unit instead of any 700r4/60e/65e based unit. I built these for years and know all their weak spot mechanically. The sprag,overrun clutch hub,3/4 clutch stack, input drum and reaction carrier shaft are ALL weak points. The sprag is #1. You guys will break these if your car hooks up to the pavement unless they program in a failsafe to make the trans upshift to a higher gear in the event of a freewheel condition....which saves the trans but takes the point of the burnout out of it. As long as you spin the rear tires your fine. If they hook, your sprag is done. 4l65 uses the sprag for all forward gears except OD where it overruns. On a hard 4-3 downshift, it will flip. Input drum is aluminum. Housing usually cracks where the input shaft splines in.
I just did a 727 and there is NO comparison in strength. The 727 is a monster. 4L80e is the only unit that compares in strength. Its up to you guys but I KNOW the 700,4L6X units and their weaknesses. Now if you are using a 4L8X based unit, then NO WORRIES as it is the old TH400 with overdrive added onto the FRONT of the geartrain whereas mopar added OD onto the REAR of the 727 geartrain.