DIY 40w laser

Hi guys looking for little advice, I'm on the completion stage of my build, 40w co2 bed size 650x450mm, using the awc608 laser control and laser cad software, when I first started the build I planed on using some nema 23 motors, these where going to be used on a cnc build but never used them, these are wired parallel 4.2 amps and 1.8nm, 200 steps 1.8 angle, now the build side went smooth but where I get stuck is the working out of numbers,

Belt is 10mm wide with 5mm pitch, pulley 20tooth,...

DIY 40w laser