Can we decipher CRANE Cam Headwork stamp?

I have a pair of 1965 289 cast iron Ford heads that have the word CRANE, C463, C55X
stamped on them. The valves are much larger (2"and 1 5/8") than stock so I figure Crane Cam must have done some work on them back in the 60's. Valve springs rest on a 1/8" deep machined recess. Does anyone know what those CRANE numbers mean? Thanks.

 

Those heads may be what they call Crane Fireball heads. Ive never seen Ford heads but have run across SBC before. As a matter of fact my 56 had a set on it way back when.The guy I got the car from says he gave 750.00 for them in like 71 or 72. Ive seen the SBC s on g***er madness for 1800.00 and up.