"I am trying to CAD up a drawing for a plate for this motor to mount to.".
I read the drawing and TinEye.com searched the photo.
For the "Star" bracket you'll need a 114.3 mm recess, 3.2 mm deep to allow for the raised inner section, with a greater than 22.23 mm through hole to allow for the shaft. The bolt hole circles are 106.4 mm and 149.2 mm diameter. Use 5/16" x 18 TPI bolts and 3/8" x 16 TPI bolts; the "Star" bracket uses all 8 bolts, the "L" bracket configuration uses only the 3/8" bolts. Of course you can combine designs and come up with your own.
Metric Conversion (rounded to nearest imperial measurement):
114.3 millimetres = 4 1/2 inches
3.2 millimetres = 1/8 inch
22.23 millimetres = 7/8 inch
106.4 millimeters = 4 3/16 inches
149.2 millimeters = 5 7/8 inches
Here are example mounting plates for that motor:
Source: http://www.electricmotorsport.com/nema-143t-c-face-1-2-inch-aluminum-l-bracket-motor-mount.html
Source: https://m.ebay.com/itm/Manta-10-hp-electric-motor-MOUNT-Etek-Briggs-Motenergy-Permanent-Magnet-STAR-NC-/391984038365?nav=SEARCH
If you are considering purchasing one of those brackets you can probably find the "L" bracket for a lower price since it looks easy to make and is priced fairly expensive at the place given in that URL. The "Star" bracket is more complicated and CNC machined, for a custom item it's price is more inline (and you may find it difficult to get someone to make you one for less).
Which of the two, or another design entirely, really depends upon what you intend to attach it to.
Those photos ought to give you a hint about how you want to draw it up and the appropriate dimensions to use. The place you bought it from probably has brackets, a drawing of the bracket might help you more than one of the motor.