I'm guessing Rod, but unless there's something in the way that presents clearance problems, they should bolt on without a hitch. The manifolds on the C4 are nothing more than tubular preformance manifolds, somewhat similar to "shortie" headers, and they manufacture those for the C2 correct?
Good luck, somebody else (like Tom or Lou) will know better than I.
The reason I ask, is that I took my the stock units off my '73 and want to use a shortie header to go back on. In reading John Lingenfelter's book on modifying small block chevy engines, he really likes this manifold. The way it is designed, it looks like I could still bolt up the A/C as well because the bolt bosses are raised.