An obscure page on the Kilmartin House web site describes Upper Largie as follows:
The site consisted of four cists and four other features (two of which may have been cists) which were situated on the summit of a gravel terrace near Kilmartin. Out of these one cist was repositioned after excavation but was later partly covered by a layby and is now largely overgrown, and the other cists are no longer apparent.
The site also states that, "this site is on private land and permission should be sought."
The easiest way to see something from Upper Largie is to visit Kilmartin House where one of the cists has been reconstructed.