The traditional and budget friendly upgrade is the Offey intake manifold with a Holley 390cfm carb. Don't forget the Landon heat plate for the manifold, using either coolant or tap into the headers for exhaust gases to heat the manifold with.
That's probably what I will do with my 250 Chevy when I finally get the cash for a head swap, but with the cheaper 292 2.5" HD exhaust manifold instead of the Langdon headers. From what I've gleaned from others who installed the Offey with the Langdon headers is that there may be a little grinding to get them to fit up.
I don't think I've seen the Clifford intake paired with the Langdon headers, so I don't know how the fit is.
