If you are so worried about redundancy, put a copper bar/tubing in place of the headlight switch fuse or wire across the clips. Silly, but if you have a hang up, that will ease it. Using the 55-59 V8 switch and the 55-59 dimmer switch is a no brainer. You mention reducing redundancy and ignore that you may be creating problems with trying to wire in/adapt non correct parts/switches? There are connectors for the dimmer or just use female spade terminals with shrink sleeving. I have rewired 55-59 with new harnesses several times using these original switches and newer fuse panels. Bill probably has also. No problems. "Additional parts" do not fail.
Converting to a V8? With an electric solenoid? Using a "separate auxiliary starter switch"? That's what the era correct 55-59 V8 switch is for. "A dummy for the auxiliary starter switch"? "aesthetics are everything"............does that mean the auxiliary starter switch will be hidden? Hard to reach?
You are confusing me. I don't see the logic in your plans. Maybe you are going all hot rod custom on this?

Dimmer switch connector American AutoWire PN: 500286. $5 When you say "molded connector" , I assume you mean the correct Packard 56 style used in that era.
The 55-56 Dimmer may have a different spade pattern (rotated) than 57-59. This should have no affect.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn