Hi, B5! I found the wiring diagram Mark sent with the unit I got for my '78 550 very easy to follow. There wasn't one with yours?! Install was a breeze and what an improvement in the response! The link on the page that Flybox sent you has the same diagram.
BTW, if you are running with the airbox, rather than trying to position the controller behind the batt. housing or on the frame somewhere, I just put it in the tool-tray with Velcro on the back of the controller. Ran the wires over the back of the tray and down between the frame and rear fender. Simple feed forward along the main harness after that. Piece of cake.