Are these available with the front glass shaped like our originals and not flat which is an instant give away as not being original? I want to stick with an all original appearance. I put some Hellas on my RV and they are totally flat on the front glass.
I've got Cibie on a couple of my cars. (7-inch, round, like 6012H used on most 50's, 60's cars) They are not flat, but rather, convex, shaped like originals. They take the H4-type bulb. I've had them around 30-40 years. But note, even though they have the original shape, they are still an instant giveaway, because the glass diffusion pattern is different, doesn't match original, at all. On the plus side, I think they are great, as they are substantially brighter than 6012H, and the light is 'focused', with a sharp cutoff at the top. (No stray light up in the trees)
JMHO
Looks to me like these Cibie's, with the 6V H4's that duecelover posted, would be a pretty good option for 40-55 cars.
(I see Cibie on-line, at Walmart, Amazon, e-bay, and several other places.)
(If you are looking on-line, check out VintageCarLED VCm35-7 inch kit. It's like Cibie, but the diffusion pattern is more like 6012H - ie, more like original. $209 pair)