I'd recommend taking the rifle out of the stock and stripping it right down. A lot of old rifles are full of crud below the stock line. Metal parts can be wiped and soaked in mineral spirits to remove dried grease and dirt then oiled after drying. I use sealed a jar of mineral spirits to soak and swish the metal parts, other than the barreled receiver. Fine steel wool and brake cleaner/methyl hydrate/laquer thinner do a good job on stubborn grease and crud. I use a pick-up magnet to fish out the small parts and it can be pretty amazing how many small steel filings and scrapings are found in the solution. The receiver interior and exterior can be sprayed with WD40 to loosen crud, then scrubbed with a toothbrush and re-oiled after wiping dry. Short of metal refinishing you can also use a Dremel brush and a razor blade to peel off old crud.
As mentioned, wood can be wiped with either raw linsed oil or pure tung oil to clean and re-condition it. If it is really dirty a wipe down with mineral spirits, followed by raw linseed or pure tung oil can help.
Bores need a good scubbing with a brush and solvent. De-coppering/de-fouling with an agent such as Butches Boreshine and/or JB Paste works well. Make sure all oil soaked rags are properly disposed of and only use a nylon bore brush with a de-coppering agent. They will eat a bronze brush.