This took far longer than it should have taken, simply because I was using a dull bandsaw blade.
The 1/2 x 1/2 link shown on the forward part of the brake handle in pic 2 below requires two notches - each 7/32 wide by 7/8" deep. These accomodate the brake handle itself plus the roller pulley that supports the brake cable.
The dull bandsaw blade started veering off at an angle, so took a ton of cleanup to finally enable me to get the Vixen file in there to smooth things out.
The roller used just has to be 1" in diameter. The aviation dept at Lowes had about a dozen different styles and sizes, so I settled on the one in pic 1 below. A simple nudge and the center rivet came out. The resulting hole was already at 3/16", so I didn't even have to enlarge the hole.
