Dave:
The color characteristics appear to be those of jatoba, or what Americans call "Brazilian cherry". If the wood is very hard, and a bit difficult to work with hand tools, that might be as good a guess as any. If you have any boards that have a delineated sapwood line (like walnut), it would add credence to the guess of jatoba.
The "80 year old" aspect throws me a bit, as jatoba has seen popularity in this country, mostly as flooring material, only in the last 30 years. Today there are better conservation and forest management practices in use, thanks to heightened awareness and various international programs, but considering the lumber practices of the past, where it was not uncommon to clear an acre of land to have access to 4 mahogany trees, one wonders what was done with all of the trees that were not mahogany. Perhaps this was one of them, at which point it is anybody's guess.
FWIW.
Tone