An alternative to Al's route is to take the Kilberry road out of Tarbert taking a western loop to Ardrishaig, on a good day the views over to Islay and Jura are stunning, but on a bad one it would be exposed to whatever westerly weather is on offer. In theory both options can be done but that makes for a long day, about 180 miles.
I would be happy with any route so long as it is meaningfully shorter than the 180 mile one.