I’m spoiled as I live in Helensburgh (when not working down south) and these are my home roads - no jealousy now
https://www.sabre-roads.org.uk/wiki/index.php?title=Clyde_Sea_Lochs_Trail
There really are some fantastic driving roads around here - be careful on the A82 going through Dumbarton though - BIG police HQ there & usually a few speed traps & cruising traffic cars.
A good addition to before and/or after the NC 500 or just on it’s own if you don’t want to go so far, driving up the West coast of Scotland is phenomenal - I would,if I where you, use this as a base for a touring holiday on the West coast - you will enjoy it - promise.