relay for ignition switch elimination?

A customer bought me a hot rod to wire from the ground up. One of the things he wants me to connect is an ignition switch eliminator. This kit he provided utilizes 2 relays. One is the normal ISO relay and the other is slightly larger, metal case and has 1/4" terminals marked: S, 30, 56, 56a and 56b. There is no brand name but I get the sense it's German manufactured.

The 56a terminal is by itself as the other 4 are grouped together. On the top of the case there is a clip to snap it into a hole.

The reason I'm asking for help is that all of the wires provided are single, without a common connector and 2 were disconnected and the printed diagram on the side of the case is mostly worn off and no instruction sheet is available.

Using a push button, on/off switch with 2 wires connecting to the 2 relays, this is supposed to start the car while depressing the switch, run the car when released and turn the car off when depressed again. The switch has a 3rd wire connected to ground.

I have battery power going to terminals 87, 56a and 56. Terminals 85 and 56b are connected common with a wire going to the switch. Terminals S and 86 and wired common with  a diode or resistor between them and a wire going to the switch. Terminals 30 and 56a were disconnected and I don't know which one should be connected to the "Start" and "Run" circuits of the car.

Also, the battery feed wire provided is 12ga. This doesn't seem large enough to run the entire car (40 amp relay) to me.

Any help, thoughts or comments would be appreciated.