thats a 1966 200ci. same code as the one in my 66 mustang.
the only real difference with the 68 engine is the distributor, carb, and a larger exhaust manifold. you dont have the annoying SCV and load o matic distributor(points), the 68 has the duraspark (electronic ignition). the exhaust manifold is a larger volume, with a 2" outlet (compared to the 1 3/4" outlet on the 66). if you want the numbers to match, then get a 66 200, but the 68 is actually a little better. your sig says its a sprint 200 so if i were you i would get the 66 200.
if you do keep the 68 motor in and arent concerned with the correct numbers, swap on the head from the 78. it has a larger intake manifold, larger valves, and hardened valve seats for use with unleaded gas. the downside is that the combustion chambers are 62cc, whereas the 66 and 68 have 52cc combustion chambers. if you mill it .075 it compensate for the thicker head gasket as well as the larger combustion chambers. you could also get a 68 exhaust system, its larger.
Ford Six Performance: The Web's Leading Resource for Ford Inline Six-Cylinder Engines and Cars! <-- good forum if you have any more questions. oh and buy the book.
anyone got a 200 6 cyl 
