Finally got the wiring harness installed. It works fine and there is a definite difference in tone. I don't know what words to use to accurately describe the difference but it's very noticeable. I'm glad I made the change.

I'd say at this point my SG is nearly as good as it's going to get. In addition to the new harness it has upgraded locking tuners, a String Butler, a roller bridge, a vibrato and strap locks. I recently took a 1 day course to learn how to properly set up a guitar. Once all my tools arrive that'll be the last thing to do.