That head is definitely from the 1950 to 52 216/235 type of motor. It doesn't fit any other type. As far as whether it is a 216 or a 235, that is a little tougher. I don't think the casting numbers will tell you that. That motor is the same as type as I have in my truck. I learned a lot of these details when looking for a replacement head. Here is a photo in my Webshots. If you look at the head between the front two plugs you will see the smooth area.

Head Photo My Truck

1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed

My Chevy Master 4 Door is on the Road!