First post, hello everyone...
I have a project or 2 with USACG necks and have followed your build with interest. You're doing great. As a rookie at DIY nitro/finishing, I've also learned from my mistakes.
Only 1 comment: the pic of the neck looks like the headstock has not been reduced in thickness. The USACG necks I have worked with are greater than 0.560" in thickness so I have had to block sand the back of the headstock to bring it to spec. If you don't do this, the Gotoh vintage tuners will be "shorter" when installed due to the incorrect greater thickness of the headstock.
If you're using a different tuner set and have adjusted for the headstock thickness, well then nevermind, you've got it under control.

Look forward to the continuing story of this build.