Yes it can be done. You need to work each cylinder while it is at TDC (top dead center) or the best method is if you have an air compressor and a hose from a compression gauge you can put air pressure into the cylinder through the plug hole to keep the valves from falling into the engine. You will need a valve spring compressor I have an old one like the $13.25 cheapie in the link but I would recommend getting a better one for your first experience with valve seals. I believe this procedure will have lots of information on the internet and in repair manuals for your engine. Try Google "replacing valve seals on a small block chevrolet". Good luck,
Vern

1953 Chevrolet 3600
Fried Green T'mater (Vern)
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Man who runs in front of car gets tired, man who runs behind car gets exhausted.