In reply to Milesy: Seconded not had breakfast there but it was the place that introduced me to the culinary magnificent that is cheesey chips: calorific heaven.
For a value fry-up you could try the pub called the Stonefield at Milton near Dumbarton, right on the A82: their £3.89 carvery is another good calory whack, all the veg and roasties you can eat, and they do a full Scottish for £2.99.
And - if the Pit Stop is shut there's a shack at the garage at Arrochar which is OL fopr a bacon roll.