Why not get a 151 Chevy 4cyl, used in the Chevy II's tons of performance parts and it'd be a lot simpler however, you could modify the manifold to fit a 4bbl. I'd find a 151 or 181 Chevy, the 181's and 151's were both used in marine aplications, the 151 head from the marine engines are supposto be better heads.
