kmcrawford111
That Bafang CST is a great motor. It may be perfect for what you need (you just have to figure out which motor code you need).
If you want to be single speed, you can use a single speed cog on it, with the appropriate spacers to put the cog in whatever chainline you need. That is roughly what I did on a non-electric conversion like that. I just don’t know how you can adjust the chainline if you use a screw on cassette.
Why do the motors use an old design screw on cassette? Well most of them are manufactured, bought, and sold in China.
Personally I wouldn’t put a front motor over 250watt on their unless you have a steel fork. Any kind of shock loading with torque will snap off those light alloy fork ends.