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There will be a spec for the type of gear and the type dictates the tooth profile. You don't ned drawings, you just need to know what type of gear it is. I'm unfamiliar with that lathe. You might try calling Boston Gear, or the manufacturer, or see if there's a manual that will have the change gear spec. Once you have that, it's a simple matter of looking up the gear profiles and clearances. Then just CAD it out.
Heck, you might even be able to take some photos of your existing gears and then matching that up with common gear profiles to determine what info you need.