Jeff........the 8N came from the factory 6-volt positive (+) ground. The genny is on the LEFT side of the engine and have a 5-nipple dizzy on the right side of engine.
Many N-Tractors have been converted to 12-volts negative (-) ground with GM Delco 10SI ALTERNATOR. They are mounted the same place as the original generator ...except... alternators require different mounting brackets.
It should be intuitively obvious, a 12-volt conversion requires a 12-volt battery. (12-volt battery has 6-water fill'em-ups) ........Dell, a 12-volt advocate for the right reason, who knows 8-ways to convert to 12-volts and they all work the first time