Hi Nick,
I did a similar thing back in April, took photos of the first one (coming from Kenmore) but not the second, and was sure they'd be on the map when I got home (although I couldn't remember seeing any reference to them anywhere before). I think one of them is between Ardtalnaig and Ardeonaig and the other is maybe around Tullochan, but like you I didn't have anything to make notes with.
Been meaning to go back there to get grid refs. Certainly didn't look modern from the road.
Cheers
Andy