It really doesn't matter which you run to, the battery positive or the live terminal on the starter solenoid, the battery post usually has too many on already and it depends on where you mount the relay, close to the battery or close to the starter
Not the one that connects to the starter motor, the one that connects to the battery.
Here are the drawing files, but no perving at Carl's girlfriend mind you. Scroll down without looking!
http://www.thisoldtractor.com/guzzi007/sportissimo.html