1942 Mercury dash starter button wiring with 12v solinoid.

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Ties into my solinoid thread, but that one has runs it's course, so starting a new inquiry. I've got the 4 position keyed Bubba ignition working and going through the 12v solinoid grounded to the firewall. Negative ground system. I'd like to add the push button starter into the mix so that I can turn the key to the run position and either start with key or use the push button.

Push button I have has only one wire and I presume this would be hot with the clips on the button grounding the switch to the dash. But if my system is now negative ground and I want to run this one wire from the botton switch to the solinoid, do I need a seperate ground to the switch? Will this one terminal switch do what I want it to do? Or should I look for a replacement swith with two leads?
Here is pic of current (no pun intended) solinoid set up. Any guideance appreciated.