I collect and restore fords..got plenty of them.. including a 2n that is essentially the same as a 9n, and it is 12v.
the 6v starter works FINE on 12v, and lasts nearly as long as when run on 6v, spins faster.. just don't grind on it forever.
9n/2n don't use starter solenoids.. they have a mechanical interlocked start switch.. the big thumb button on the tranny presses a jiggle stick thru an interlock plate.. this stick manually actuates a high current switch that is mounted to the back of the steering pedistal.. no need to change it... it is actually overrated once you swap to 12v.
lamps need to be changed.
if you keep the oem 6v coil, then you need the oem
ballast resistor plus another .5-1 ohm of resistance.. stock resistor like an 8ne10306 will be good for about .5 ohm.. or you can use radioshack 271-130 .47 ohm resistors.. note.. 2 might be needed.. there are plenty of different variety of 6v and 12v coils out on the market right now.. I've seen as much as 2 - 2.5 ohms of extra ressitance needed on the cheap overseas coils that only have .8/.9 ohms of primary resistance..
alternately, you can get a 12v front mount square coil AND run the ballast resistor with them.. the 12v coils are unfortunately only happy on 12v.. not on 14v where charge votlage is at ( way to go china! ).
Easiest way to make sure you have enough primary resistance for your coil primary is to install an ammeter inline with your ignition coil.. bump the engine over till points close.. shoot for 3-4a of primary current.. if you get in that range.. you are good to go for long breaker contact and coil life.
yes, you can get a genny rewound for 12v.. or you can hang a delco 10si/12si alt on it.. if so.. get a 3 wire job.. charge wire to the bat side of the old cutout relay... #2 terminal jumped to the charge stud, #1 terminal run thru a 194 marker lamp to the coil side of the ignition switch.. or you can use a diode like a 1n5408.. or anything 1a/50piv or better. 3a/200piv is reccomended... install with the marked side of the diode ( cathode ) towards the alternator.. run negative ground
soundguy