Engine test stand wiring??

Almost impossible to answer without "the parts" you have or are going to use in front of you

Gauges wiring? Depends on the gauges. You planning on using a relay of some sort for the start relay or just a simple heavy duty push button?

What all is going to be wired up? Electric fuel pump? Water pump? EFI? etc?

Some good clear photos of what you have for a control panel would help
I will get it all mocked up and ask further. I appreciate the help.