Pulley Selection / Requirements for Servo System

I am retrofitting a bridgeport 9x42 clone and have 19lb-in servos. I
now need the pulleys and I want to be sure I get what I need.

My assumptions:
Belt width: greater than 3/4"
Pitch: Approx. 5mm.
25 Teeth on Motor Pulley
50 Teeth on Screw Pulley

What is a standard set up on a bridgeport?

Does it matter what material the pulleys are made of? I have seen
Aluminum and multiple steel types.

Will two set screws be good enough or should I use a taper lock
bushing type?

Then where to buy? I have looked at McMaster and they don't have
much of a selection. I have also looked at Gates and they are
expensive.

Thanks,
John

Thanks,

John