I have used a Hole saw and drill press.
I also use my lathe to turn down the width of the gear on the right side to lighten it.
Depends what tools you have and what you can afford.
Easy to scribe and figure out.
If I remember right from the V of the tooth in .700 and 1.100 between holes.
That is GH's 2003 USLMRA Championship motor.
Hope that helps.
OH 5/8 or 3/4 hole saw