Offenhauser still makes them - look on the summit or jegs web site. It is a single plane with short runners so can take some tinkering to run right on the street.
PS: I run two eddy 500s on my 340 on an STR-12 - yet another "idiot". If you run an inline 2X4 I think Eddy makes a matched set of carbs for a tunnel ram that are tuned for front and back carbs for dual quads
