Thankyou. I did steal it -- it was $10 plus $10 shipping from e-bay. The seller called it a Hot Rod headlight, only one. Since only one, no one wanted it. It was actually a 7" bottom mount headlight for a Harley, selling for about $200 new. Picture of mine and verslagen's, and the mount:
The mount was four pieces of 1" x 1.5" x .125" aluminum angle, eight small nuts and bolts on the sides, drilled down for the stock mount, drilled one up for the headlight. Simple, cheap, worked just fine.
A Model-B headlight bucket is a 8", available aftermarket with an H4 lamp. I think the Model-9" was bigger, but shallow front to back and is ugly.