manual valve body 727 trans question

I just purchased a mopar with a reverse manual valve body trans. Unfortunately the shifter doesn't work with it without pulling T handle from each gear (doesn't rachet backwards). Will it hurt the trans to drive it in 3rd all of the time? I don't plan on racing the car. Maybe I should put a normal trans back in it?? It's a pain in the *** to drive shifting through all 3 gears with the current shifter.
Can it be changed back to a regular trans or what it be better to have another one built?