Bill Houghton, Sebastopol, CA
If you've got that plane body in your shop, and a protractor of some kind, and a suitable piece of steel that you can insert and wedge temporarily in place, it would be easy enough to figure out.

If, of course, your only contact with that plane is through the internet, it gets harder.

I've got a wooden miter plane on which the iron beds at about 30 degrees, just barely enough clearance behind (with a 25 degree bevel) to allow it to be bevel-down.