As I recall the use of '40 Chevy headlights on a '36 Ford originated in the San Francisco Bay area, usually with a Packard or LaSalle grille. The car magazines of the mid 50's generally referred to use of Chevy headlights on a Ford as the "Bay Area Look".
I did not drift off of the original topic on purpose. Others mentioned halogen and/or 12v, it was my intent to show that 6v lights can work very well if they are wired correctly.
regardless of what the power source is, 6 or 12v the actual power comes from the amps supplied to the point of use. The natural high resistance of 6v requires the best wiring to make things work correctly.
The current headlights on my '36 are stock '36 pods with 6v sealed beams using a conversion for '35-36 Ford trucks and truck bezels. The '40 Chevy wiring, relay, switch and dimmer is still in the car.