The casting number tells you exactly which head you have. The 194 head is for a '68 or early '69 1 bbl 250 engine and has the largest combustion chamber. That gives you about 9:1 compression on a 250 engine which is a good number for using regular gas for the street. You can find either another 194 head or the 456 head (late '69 1 bbl head) to replace that head. You shouldn't have much trouble.