Why do the gasket sets come with a gasket for mounting the starter? Did Ford use a gasket there? Seems like it would just reduce the quality of the electrical ground for the starter.
I think the idea of the gasket (or gaskets) is to shim the starter so that the gear on the end of the shaft sits closer to the ring gear on the flywheel.
I have heard several say that this is more prevelant when using the more modern style Bendix drive.
I agree with you that it would seem to cut down on the grounding aspect of the starter mounting. Too many shims would also affect how the starter sits in its recess.