Hi Ed,
Thanks for taking the time to post the pictures.
Looks like your car is red, and the cut out, looks like is it in the radiator support? Looks like it's painted white?
You changed your car to negative ground? I could not get LED's to work on my positive ground car.
I was at Radio Shack looking for toggle switches that light up when on, the other day. I think I saw push buttons like yours that light up when depressed. In case that interests you.
Cheers, Roger