The problem with many RC papers is they have some developer in the emulsion. Some will say, and some won't. However, you can get many to lith as Dr. P recommened, by bleaching and redeveloping in lith. I have found that you generally get a better response with a copper sulfate bleach, or add salt to the KBr/ferricyanide bleach. I have not tried eliminating the KBr completely in favor of salt to see if it would produce a warmer response.
In any event, I would keep the old brown separate from the other old brown you may have from proven papers.