Here are a couple options:
6 volt LED taillight conversion for 1935 Ford:
There used to be a guy on Ebay who made an LED board conversion for 35s. If you can find them, I think they will work in the stock taillights; you will probably want to measure to make sure. If I were doing the restoration I would also order a pair of Bay15d empty bulb bases and solder the leads from the LED boards into the bases so I didn't have to modify the wiring on the car in any way.
6 volt LED 1157 taillight bulbs:
http://www.superbrightleds.com/cgi-b...R#1157-W12-24V
I think part number
1157-R19-6V LED is what I have in my 37 right now and it is much better than incandescent. These will also work in the 1935, but I think the board listed above will provide more light.
Note that stock prewar Fords have a bulb socket that does not accept an 1157 style base. To remedy this you file the higher, I think, tang off the side of the bulb. Then you just have to make sure you don't put the bulb in so the tail light circuit operates the brake lights, and vise-versa.
and since this is a long post already, if you are interested in upgrading your headlights:
6 volt halogen bulbs that fit the stock 1935 Ford reflector:
http://www.lbcarco.com/
search for
halogen 6V
I think part number
170-957H is what you want.
New stock reflector for 1935 Ford:
http://store.bobdrake.com/19pas19pucom2.html
New stock headlight lens for 1935 Ford:
http://store.bobdrake.com/19pas19pic199.html