Smiths Elec Tach W/Power Arc

In the final stages of getting the Mark 3 back on the road. Installing the Elect Tach with the Power Arc ignition installed.
Question; Is the Power Arc considered an ECU and do I wire it accordingly the White/Black from the Tach to the Green exiting the Power Arc. Or due I use the Red/Blue from the Tach to coil.
I currently have the White/Black connected the Green from the Power Arc. Not applying power till confirmation. Bike budget is bottomed out!

Chuck

Forgot to add, its a negative ground system.

You have two alternatives.

Either use the red/blue on the tachometer to the coil.
This is my preference as it means you can swap out the electronic ignition or revert to points with no issue.

Or you can connect the white/black to the green tacho wire on bye Power Arc.

Both work fine, are as good as each other, but you can only do one.

Thanks, I'll stick with the White/Black and fire it up.

Chuck