[Rory McNeil]

The 351 Cleveland didn`t come out until 1970. The 351W debuted in 69. As for the Cleveland heads, the 70-73 4 barrels had larger valves and ports than a 2 barrel version. The 70-early71 4v heads also had smaller combustion chambers than the 2 v or late 71-73 4 barrel castings.I heard that there was an oddball "smaller" 4 barrel head towards the end of the 351C`s production run, but I`ve never seen them myself.
As for the 351W heads, I believe the heads are the same for 2 or 4 barrel applications.