The SBC thermostat fits perfectly in a 216. I recommend a "fail safe" thermostat. These thermostats "pop open" when they fail or get stuck, thus reducing the chance for a over heating situation.
Tim
"Pay attention to the details! It ALWAYS pays off."
1949 Chevrolet 3100 Series 1/2 ton Pickup 1964 Chevrolet C10 (Ol' Yella) (SOLD) 1958 Chevrolet Biscayne 2 door (SOLD) 1970 VW Beetle