The dimple to provide  rotor clearance.

 Getting close on fitting the brake tab.

 Quite the erector set!  But, with judicious
 measuring and machinists squares, it's right on the money at
 50 mm rake and 370 mm axle to crown.

 The beautiful lug to be modified.

 The die grinder and carbide bit made short work of finishing up the top tube lug removal.

Now to fit the patch.I used a scrap of 31.8 mm head tube and reformed it to 28.6 mm I.D. to match the lug.