On that MSD box I would not even bother with the start retard function. I would just use a simple
spark power interupt toggle switch. This box does not actually have a dedicated cranking start retard function.
You have to use the step retard.for it. in "RPM mode" (small pink wire needs 12 volts)
A spark interupt toggle switch is easier and better. Make sure all the retard ramps and delays etc etc are disabled.
You want no retards active.
The simple interupt toggle switch goes on the small red swtiching on/off wire on MSD box.
it just turns the box on and off. You can't screw it up. You will find it second nature in a very short time.
crank it over 1-2-3 count and throw the switch to give it spark. It is just that simple.