RPM signal from a coil

Hi, I’m looking at purchasing an adu5 for my formula Vee, as we don’t have an ECU how can I get the RPM signal? My current dash runs off the negative of the ignition coil and through an RPM filter (a product made by AIM) can I do something similar to this?

I think you could use pickup like this: MSD 8918 MSD Tach Signal GMR Pickup

Edit: you said you already have one. So you just connect that similar like your current Dash. Something like this:

Great, thanks for your help