If you’re doing Moffat to Inverness I’d recommend going up via the Cairngorms. Absolutely brilliant roads and only about two miles of motorway and dual carriageway the route I tookThis is a great book and I have found it invaluable in planning at NC500 route, especially the route up to Inverness from Moffat where we are staying the night before. That said, I may change that booking and get the M74 out of the way and stay nearer Glasgow. In any event, the idea of skipping Loch Lomond and taking the road to Faslane sounds great.
If you’re doing Moffat to Inverness I’d recommend going up via the Cairngorms. Absolutely brilliant roads and only about two miles of motorway and dual carriageway the route I took