What we know of the history of the Club is that Ross did work there prior to Tillinghast. A rough diagram of his routing is on display, among other great memorabilia, as you enter the Clubhouse. Tillinghast was brought in following the purchase of the land where 2-8 now exist.
The 10th green pre-dates Ross, some consider it to be one of the oldest active greensites in the US. Any features that Tillie may have left unchanged remained on holes 16 & 18, however those features have been modified in recent years to resemble more of the evolved Tillie bunkers. Evolved in that the bunkers were originally grassed face and are now flashed and will remain flashed.
Tom,
Even though nothing may exist at the Tuft's Archives that does not mean Ross was not involved. While doing research for many of our projects we do not always find info. at Tuft's.
Newport truly is a Tillinghast course.