Dixco Hood Tach Wiring Help

I bought a replacement Dixco Hood Tach for my 1965 Dart 270 Conv. Yes, I know...it’s not original, that’s not the point.

Old tach had four wires, new tach has three. I have four wires coming through the hood.

Can anyone offer a color to color combination to help me out? Photo for reference below. I’m thinking:

Black to Black
Both Reds to Red
Gray to Green.

Thoughts?