THE VICTORIA SHOWN HERE has not always been one. A ’50 Ford, it was in fact a convertible before its owner, Elton Kantor, of Oakland, Calif., decided to make it eligible for the Bay Area Customs Club. Eight months and $5500 later (including the car’s original price) it became very much so, as the photos show. To the everlasting credit of Joe Bailon, its builder, the car achieves its undeniably striking appearance with a minimum of protuberances and sudden surprises in color and line. It is brilliant metallic blue; inside, black and eggshell leatherette covers the seats, roof, and side panels. That low look is no illusion: A stock Ford Victoria roof was chopped 4 ¼ inches, and the frame was stepped to 4 ¾ inches road clearance. Rear bumper,…