Grady,
Put on your Manhattan Trophy Hat for me . . . if danger to the oil system were not an issue, what would your opinion be of the above bead-blasted case? I like the fact that the finish is uniform and it would provide a good basis for "patina" to form over the years, but if you think it would irreversibly doom the effort I'll think otherwise.
Trivia: Years ago, before I was seduced by Wall Street, I ran a sodium bicarbonate blasting business. The finish is excellent, damage to the substrate minimal, and the media dissolves with a dip in hot water. There is a contractor down in Westchester county that I believe could make quick work of the case, with much less danger of residual contamination than any other media (except, as Kenik points out, Dry Ice Pellets, which is a process so expensive that only Boeing uses it!)
While we're looking at cases here's one you should all recognize. . .
