351C is a low deck, canted valve design. The heads appear similar to the 429/460 or a BBC. It is no kin to the 260/289/302/351W family of inline valve engines. 351C has 8-bolt valve covers, 351W has 6-bolt valve covers. The 351M/400 tall deck is a variant in the Cleveland family, but doesn't lend itself to hot-rodding like the 351C.
The 70&71 4 Barrel (351C-4V) was available with quench heads and the monster ports (You could fit a pack of cigs down the intake ports), but in 72 they were replaced by open-chamber heads, still with the large ports. 2 barrel heads had much smaller ports and open chambers, as did the 351M/400. The 351C survived until 1974; in 1975 it was replaced with the 351M/400.
The Boss 351 , a specialized 351C-4V with screw-in studs, hotter cam, etc., was really the most streetable of the 3 Bosses (302, 351, and 429). It had a generous torque curve and plenty of breathing for the top-end.
More about ***** than some of you wanted to know, but it the 351C-4V is a good engine and worthy of respect.
