I Dont have any parts bought yet, except i have high indtuctance stepper motor from my previous build and tb6550 drivers with BOB which i am not sure if to use them.
You would cripple the machine if you used them. Have a look for AM882 drives and nema 23 motors from Zapp or CNC4you.

Re the screws you will probably requite the F dimension to be about 30mm it doesn't cost much more to do it right.