I hate that name, NC 500. Call it a road trip with no fixed agenda. Personally I would go anti clockwise from Inverness, slow meander up coast towards JoG, along the top taking in Bettyhill, Durness, great craft village at Durness, down to Scourie, crossing Kylestrom bridge hang left towards Clashnessie, Achmelvich Bay is a must, then down Lochinver. If heading to the Applecross Peninsula, the world famous Inn is a must eat. Then doon the Bealach Na Ba (the pass of the cattle) better going towards Kishorn, as the views are better.
Remember, much of these roads are single track and can be challenging and not for the faint hearted.