Athlon might be a good place to start. It is all just circles.

Two systems of measurement on rings from the top of the rail; to the centerline of the scope or to the bottom of the tube.

Action: 34.29mm or 1.350"
Barrel approximate OD : 25.4 or 1.000"
Athlon scope tube: 25.4, 30, 35 mm. Radius 14.7, 15, 17 mm
Base height above the action" XX mm or XX"
Athlon Scope Objective OD: XX mm or XX"
Clearance you desire between objective OD and barrel: XX mm or XX"

You should be able to calculate within a 1/16th of an inch or 1.5 mm.