Meant to say, weather-wise, late October in the West Highlands could be utterly grim or it could be perfect. If you can, make your plans as late as possible when you've seen a forecast.
It's worth knowing that that part of the Highlands is probably the wettest and that it can be a good bit drier further north and/or east. So if it's looking shit you could press on up the Great Glen to the much drier Strathnairn area south of Inverness (Ruthven, Brin, Rooftown etc), or the north west (Torridon, Applecross, Ullapool etc).