Treat the fingerboard with lemon oil. Go ahead and polish the guitar. The Alembic polish won't hurt, and patina on a guitar is a very different story from patina on a Tiffany brass lamp. The issue with guitars is not cleaning them. Rather, it is refinishing them. You can do the best refinish in the world on a pre-CBS Strat that looks like hell, and easily devalue it by $10K! But, as a general rule, people are not interested in preserving built up crud and grime on guitars. At least that's my experience.
Bill, tgo