Nice simple design, gotta love it.
I would think that the 'hinge point' doesn't need to be any more than a hole with a bolt through it (shoulder bolt if you can find one). Put in a couple of bushings (bronze) and some non-metallic washers between the bars and the bolt could connect the two halves of the 'mechanism' and the end of the rod actuator (or linear slide). The attachment point at the two ends could again be shoulder bolts and bushings, just round the corners off the flat bar if it becomes an interference point.
This is such a nice simple easily maintained and installed design, don't make it harder that it needs to be.
2003 Pace Arrow 36B, W22 Chassis
Ultrapower ECM upgrade, CAI, Wires, Koni FSD