In general, I think dual carbs is overkill for any unmodified engine. I have dual 1bbl carbs, but my 235 is bored .030 over and I have a mild cam, so dual carbs don't overwhelm the engine. I've seen four barrels on 235s, but I think that's overcarburetion. I did it for performance, and it paid off. The truck runs great, has plenty of power and takes off like a scalded dog.
My gas mileage is about 13 to 14 mpg, but I don't know what it was with a single 1 bbl and a stock engine, so I have no idea if that's better, worse or about the same.
