As I continue to research the 13 Colonies/States troops for purpose of identifying the uniforms that were worn, I have found a few excellent Sources.
1. Charles M. Leffert's Uniform of the American, British, French, and German Armies in the War of the American Revolution. New York: New-York Historical Society, 1926. Note: At scrcalifornia.com>uniforms>uniforms, there is a bio on Leffert and then a Linkable Index that takes you to each painting. Or if you do a query for Leffert and California SAR, you will eventually see the address on a selection.
2. Don Troiani, Earl J. Coates, and James J. Kochan. Don Troiant's Soldiers in America, 1754-1865. Harrisburg, Pa.: Stackpole Books, 1998.
3. Don Troiani also has an excellent Website (dontroiani.com) and a Facebook page entitled Don Troiani Historical Artist. Has 98K followers. It is interesting because he sometimes shows how he uses Period dressed people as models for his art work.
4. Trial and Error exploring National, State, and Chapter Webpages for their photo albums. Some are very good on variety of uniforms they use.
5. Museums, Historical Sites, Battlefield Sites, Famous paintings of events, NPS, or a query on an officers, etc. can all produce photos or pictures of uniforms.