What would YOU do with a slant six?

1966 dart wagon said
i wouldn't just throw a 4bbl on unless you have some kind of head work done, just a note. :thumbup: .100 mill, bigger valves, sivalves.com has about any size you want

perfect...haha so how much HP gain from a 2 bb to a 4bb? are 4bb bad on gasmileage?