Hello I am working on a design that incorporates a motor attached to a worm gearbox with 2 out put shafts. Each shaft than runs to a right angle gear box(1:1) which than runs to a rack and pinion setup. My question is if I want to determine the required torque to run the rack and pinion using the formula m*a*r=T, what radius should I use? The pinion will only be an inch in diameter. The right angle gearbox has bevel gears in it. Thank you in advance

You need to use the pitch radius (half the pitch diameter) of the pinion gear. If you're looking for the motor torque, you need to multiply (or divide, as appropriate) it by the reduction ratio of the right angle gearbox.