SmkRe
This is beyond the scope of of this board.
Is this for an actual design or are you trying to learn.
There are AGMA and ISo specification on calculating gear tooth loads and deflection.
The known are rpm, and torque inputs, and desired
Torque and rpm outputs. The tooth loads will dictate the type steel, heat treat, case hardening for high stress and rpm, recessed tooth pinion,
For many factors. Wear, deflection, smooth and minimal deflection.the pitch pressure angle and number of teeth will depend on all of the above.
And the the constraints of size required.
To strengthen the pinion will be the object for wear and deflection. As it will fail first.
I said recess which us an old Buckingham term. Is now called profile shift. Enlarging the pinion teeth. I don't hand calculate gear trains any more. Because the details are important. I rather use gear programs that do it faster and without errors. Or less possible errors. And to obtain
Efficient and optimal gear teeth wear. It is a very complicated process. And some gear programs are getting very sophisticated.