Just because your battery is 6V don't assume it is wired correctly or even good. New batteries can be junk out the door especially the cheaper brands. If you don't use the tractor much, you need to buy a Battery Tender (a FLOAT CHARGER) and keep it connected when not running so battery maintains a full charge otherwise it will just drain after a few weeks. There is NO switch on the RH dash panel, only the choke lever, and a mechanical device, not electrical. The light switch can be installed on the lower RH side, below the dash, on the Voltage Regulator see pix. 90% of all non-starting issues are due to incorrect wiring. Many electrical setups lack or have the proper fan belt tension, whether if a generator or an alternator is used and will never keep the battery charged if belt tension is not maintained. Don't ever 'assume'. Verify with facts and true root cause problem solving. Get the ESSENTIAL MANUALS -huge tools if ya wanna be an N-Owner. Front mount or angle (side) mount distributor? All 8N models used a 3-Wire Generator and Voltage Regulator but circuits were different for each and it matters when it comes to polarizing. The battery is the 'heart' of any system. It must sustain a full charge under load. Have it bench tested at a reliable shop. Next, get the WIRING PICTOGRAMS by JMOR along with the OEM manuals to verify wiring is correct. Use your VOM set to Continuity, NOT a test light. Don't use wire colors as shown in the OEM diagrams -they seldom are the original wiring harness and colors don't conduct electrons. Take no shortcuts and don't skip steps. The original 8N wiring electrical system consists of: 6V AG GRP 1 type battery, 3-Wire Generator with a BELT TENSIONER device, a Voltage Regulator, 3-Wire Starter Motor with a solenoid, AMMETER, correct OEM-type Ignition Switch, 6V coil, tuned distributor, OEM Ballast Resistor (front mount only), and all wired correctly. Lighting kits were never factory installed on N's -always a dealer supplied optional accessory but you say you don't have lights so no need to remove from the circuit while testing. If you have a switch on the RH dash trace the wiring. You may have a cobbled up wiring setup from a previous owner.
FORD 8N TRACTOR WIRING DIAGRAMS:
OEM 8N WIRING(6V/POS GRN) AFTER S/N 8N-263844 WITH ANGLE (SIDE) MOUNT DISTRIBUTOR:
*PICTOGRAM courtesy of JMOR
FORD 8N TRACTOR GENERATOR - POLARIZING via THE VOLTAGE REGULATOR:
FORD 8N TRACTOR ESSENTIAL OWNER/OPERATOR/PARTS/SERVICE MANUALS: