JFG,

The engine serial number (pressed into the ledge, just to the rear of where the distributor enters the block) and the vehicle ID (on the door-jamb plate) will not be the same codes.

Does your valve cover have slits in it?

Larger intake valves were used on the 235 head in 1953 and, as you stated, you have a 216 head. It looks like intake valves were the same for all 216 engines; and, the 216 exhaust valves changed in 1950 to match the 235.