I was under the impression that most of the cabinetry in our cabin was teak but would not be at all surprised to find some mahogany. They are both attractive and nautical looking.
You probably all ready know this but while the T27 while designed by the venerable S&S (Sparkman & Stevens) they were actually built by Douglass McLeod and a few hulls were made by the W.D. Schock. To complicate matters further there were some significant changes to the way the boats were made from year to year. The icing on the cake is how previous owners may have customized their own boats. The result: no two Tartan 27s are exactly alike, which is probably true for most 'production' boats.
I am pretty sure you are 100% correct about Linseed oil darkening the wood. Tung oil would be a good choice instead as it darkens less.
Tung oil - Wikipedia, the free encyclopedia
I've never seen a Tung tree which is no surprise since it grows in SE Asia.