200 or 250 are all the same head so it wouldn't matter as long as the year is right..

I doubt you'll find a 170 any year after 1970.. so just watch the casting numbers on the head..

C = 1960 the number that comes after would be the year..
so a c6 would be a 1966..
D= 1970
E= 1980

so if you want the golden head you would want a D8..

Nathan