This may help ID your engine.
http://chevy.tocmp.com/models/engine.htm Info I found on your head number said it was used in 54-62 235's.
Looking a little further using the 1929-1957 Parts Manual, I found your exhaust and intake manifold numbers
http://chevy.tocmp.com/1929_57chevyparts/57cmpc0277.htm http://chevy.tocmp.com/1929_57chevyparts/57cmpc0266.htm They are both listed for a 57 D-D (2 ton). I don't know what the D-D stands for but it certainly seems like you may have a high pressure 235 from 1957.
If I am wrong hopefully someone will come along and set us straight.
Hope this helps.
