My '55 with 292 started smoking a little bit about 3 years back. I popped both heads off and used a large C-clamp (with a notch in one end for the valve stem) to compress the valve springs facilitating removal of the valve "keepers". I cleaned the valve seat surfaces with a wire-brush attachment in a drill. I took the valves themselves and ground off the crud on the valves where they mate with the seats. Got a head-gasket set (which comes with the seals at the top of the head). After re-assembly, it didn't smoke anymore.
Took one night after work to do each head, total of two days. The dis-assembly and re-assembly I did in a couple hours each, but I'm slow and careful and detail oriented. This included cleaning with solvent and wiping parts dry. I used a pipe cleaner soaked in engine oil to lube the valve guides before putting valves back in.
Some folks will number each valve and put 'em back in the same spot. I didn't, so I had to perform a new valve lash adjustment once I started her up, but even then they were all real close to where I wanted them to be. Costed NOTHINg but for the head gasket set and i'm still good to go.
