more board track racers were singles than v-twins, but keep in mind they were race bikes first, who knows how many originals survived.
the point is, to nail the look you need a very thin motor, as one of the great tradmarks of the look is a thin overall bike (remember these bikes were just a cut hair above bicycles). Even when they use modern v-twins to build replica BTRs they always look a little too fat.
that doesn't mean you can't restyle a honda using some of the elements but one thing to consider...most of that is in frame design (dropped center section frames, under backbone gas tanks, slanted seat post, etc) and is a lot of work.