Need to elevate front brake as was required on both my Rauler Tandem and contemporary Ron Cooper built Bates, then simply flip a standard drop bolt, carefully file out the spring slot, and you are set. Add extra star washers or a spacer to clear lower headset cup.
If you can find a vintage Scott drop bolt, it will have the dual spring slots already cut, allowing simple flip installation.
Here are photo addresses to illustrate:
Kevin Kruger = Grantville, PA