All aftermarket cams are stamped on the rear face. I think the reason they don't stamp them on the front of the cam is that the cam sprocket has to fit flush and if they stamped the cam on the front, the numbers and letters would stand up off the surface and interfere with the sprocket sitting flush. I don't know this for sure, but it's the only thing that makes sense to me. Stock cams will not be stamped on the rear face.
In the 70's, Ford used some crank sprockets that retarded the camshaft by up to 8 degrees and since you have no idea what sprocket is on the crank, you have no option but to pull the cam and identify it. If you want to keep it, put it back in with the exact lifters in the exact same position and degree the camshaft.