A voltage reducer seems to the pretty standard in the power feed to the fuel gauge. The horn is usually OK, but any and all bulbs need to be swapped..dome light, dash indicator lights..any bulb you can think of.
Your coil should be changed to a internally resisted 12 volt unit, or a ballast resistor should be installed ahead of a 12 volt unit. The ballast reisitor setup requires additional wiring.
Stuart
