I'm fairly sure that I found the right wiring harness:
http://www.amazon.com/Mercury-Quicks.../dp/B004QJLGUO
Now my only question is which tachometer?
They seem to range from $50-$100. Obviously if there is a really nice one for less money that would be nice, or is it worthwhile to spend a little more?
Also, some say they only work with 4/6/8-cylinder engines, and mine is a two-cylinder.
Thanks.