So, i picked up this mini tach and installed it on my machine. It had 4 wires, one of which was the coil pickup. I connected that to the wire labeled coil front from the ECM. Everything runs fine, the tach needle moves nice, but it reads pretty low RPMs, like 500 for idle, and only about 2000 for 65 MPH. Is my ignition a single fire or dual fire ignition?

 

Your ignition fires one cylinder at a time. I had the same problem with a tach that a customer supplied. There is an item that advertises it can make tachs like that work, but it doesn't. Contact the manufacturer and see what they say.
John