FEC - to replace the headlight with an LED, you will need a superbright white LED (1,000 millicandella - mcd or 1 candella - cd - minimum or higher), a 1N4001 Diode, and a 560 or 610 ohm 1/4 watt resistor. Solder the resistor, 1N4001 diode, and the bright white LED in series, using heat shrink tubing to protect the exposed wires. Also add some flexible wire from each end connection. Note the cathode and anode connections for the diodes.
anode is this end —> -----l>l---- <----and cathode is this end
------////----------l>l------------l>l-------
Lineup above is 560ohm, 1N4001, LED
Connect the wires to the common (base of the F3) and to the pickup rollers (AC hot).
You will have to fabricate a mounting backet off of the original bulb mount and point the LED axially into the F3 headlight lens as white LEDs focus most of their light energy out the end of the LED. You will find the brightness increases with narrower beamwidth. White LEDS are typically sold in 20 degree, 50 degree, 70 degree, etc., beamwidths.
You can get the resistor and 1N4001 didode at Radio Shack. You will typically have to find a local electronics supplier or a web supplier for the super bright white LEDs.
Chi Wing on E-Bay has been a reliable supplier, good prices, delivery is from Hong Kong and takes a couple of weeks.
Richmond Controls is a supplier and has the warm white (not so blue - but less intensity due to manf process for warm white vs blue) LEDs.
http://www.richmondcontrols.com/
Hosfelt is another reliable supplier
http://www.hosfelt.com/
Have fun!
Roy