You know, I just thought of something. It's a bushing. Get some aluminum stock and buy some Moog offset bushings. Turn you some down in aluminum in a lathe. Drill a hole and tap them for grease fittings. Done deal Lucille. How hard can it be?
That will make them into plain bearings/solid bushings...
But that will bind when the A-arm is moved up and down after you adjust the front and rear cam eccentrics in/out and up/down. If the inside holes are kept on the same axis, there will not be any binding. But that will only happen if the front and rear cam eccentrics are rotated exactly the same. And that will only allow caster adjustment.