noble527.........it matters, look CLOSELY at yer 2-posts on yer genny. One is INSULATED (plastic) and the other is GROUND. do NOT connect yer 6-volt charger to GROUND ...or... you will buying a new (and rare) 6-volt charger.
ALL squarecan ignition coils used on the weird 9N 4-nipple dizzy, require the MANDATORY "infamous ballast resistor. NO ARGUE!!!
As fer the "3-wire" ballast resistor question. One of the terminals is the BATTERY source. And the source provides electricity to one of the ignition switch terminals. The ignition switch then provides electricity to one-side of the MANDATORY ballast resistor and the OTHER side of the ballast resistor, a wire goes thru the sparkie tube to the top of the squarecan ignition coil terminal.
You do know that you MUST "polarize" yer 2-terminal roundcan cut-out underneath the battery tray on the steering column, don't you??? Just "arc-spark" the 2-terminals together, engine OFF. I use a pair of pliers handles, you can use bailin'warr iff'n you want. You can re-polarize as many times as it takes to feel warm'n'fuzzy ...er... charging.
As a side note; adjust yer 3rd-brush so yer ammeter reads about 5-amps charge (+) at 1/3-throttle. Gennys do NOT charge at idle. .......the charged Dell