In reply to pasbury:
It was the Fisherfield Forest, although. looking at a 1958 survey, they simply stopped drawing contour lines when they ran out of information.
A'Mhaighdean: highest contour 2850 feet; current height 3172 feet
Ruadh Stac Mor: 2850; 3012
Beinn Tarsuinn: 2850; 3074
Beinn a' Chladheimh: 2800; 2999
and some others were a bit ropy as well. Not the easiest area to survey on foot.