Personally, I'm a fan of the Tektro aero levers. I wouldn't use them on my 1974 Paramount. But I have used them on other vintage bikes. Picture from an ebay listing. These come in black or gum. Functionally, I prefer aero levers. But on a top of the line, vintage bike rebuild, not so much. By the late 1980s, many bikes came with aero levers.

I have them on my 1988 Cimarron drop bar bike. Which of course, was a flat bar bike originally.