Hey,
I would check with Len on the Tearjerker site about matching outside skin. He has built a mini Shasta and bent his own matching panels. He might fix you up with some for your project, or tell you where to get some--He's somewhat of a Guru when it comes to Shastas.
Welcome to the forum, good luck on your build, and look forward to seeing you at Racoon Holler gathering next year.
Til later by the fire--John T. & Linda
