Based on what I've seen and read, the 200 oz-in stepper should work for your set up. If my calulations are correct, your travels are about 32" x 32".
If you are buying new, my personal opinion is to buy a step larger than what you think you need. In this case it would be around a 300-350 oz-in. Keep in mind that a stronger stepper will help with tight spots and binding that will show up in a hand made machine. The end result will be faster rapid ability with the stronger stepper.
Again, this is based on reading the many posts about this subject. Not based on math or formulas of any kind, just a gut feeling.
Best of luck with your project, it appears you have a good start. I would know more about it but I can't read whatever language it is at your forum.