cylinder head casting number question

I found out about a set of small block heads through a friend and I contacted the guy that has them, I asked him to send me pics of the heads along with casting numbers. there are no valves, in them in the pics and he's not sure if he has the valves but anyway the casting numbers he took pics of are on the combustion chamber side and they are 3418915 K and 3418915 C. whats up with the K and the C. he didn't give me a pic to see if they are j heads or not, I have to drive a little way to get em, and I can get them pretty cheap. do the K and the C make them anything special or are they just 915's. are they worth the ride probably 1 1/2 hours each way. thanks guys