Not too bad for a "rookie" Ritchie. I like those clips on the frame in the last photo. Where did you find those?
That's factory GM stuff, you should be able to get them at Autozone or similar.
I am still deciding what to use to protect the wires from the harness to the tailights. I like the asphalt coated woven stuff because its kinda "old school" but maybe the split type is more practical. Feeding wire that has installed terminals does not look like fun. What is the best i.d. to use?
Painless Performance, Keep It Clean Wiring, and others now have loom available that looks similar to the asphalt stuff but is split. Have a look at it.