It would be interesting to know exactly what that oil finish actually is, and then find something that would be compatible to use as a sealer and filler for the large pores. As damascus notes, common shellac might do it, but I wonder if using enough to fill the pores would shrink over time. Of course, a shellac topcoat could easily be removed with alcohol.
I have often thought about spraying two part Automotive Urethane Clear Coat as a gun stock finish. I need to prep an old stock to have ready to shoot with a couple coats of clear the next time I am painting a vehicle using base/clear. Carefully masking off any checkering with painters tape would be important. I think a few coats would easily fill most pores, and it would be easy to wet sand and polish to a nice smooth surface without cutting through... assuming it was compatible with the substrate. Of course, you would probably be stuck with the low VOC Clear Coat in Kalifornia, and I don't hear rave reviews about it.
Maybe find a Body Shop in Arizona that would hose it down with the good stuff...
