nicely done. a few question/comment
-how much effort (time and money) are you willing to put into this? I ask b/c this is one of those do it once/do it right type of things.
-What is free may not be what is best for your purpose. The older stuff doesn't have as much adjustment, so be aware there. Something that allows for quite a bit of adjustment (like Vuka alumina) may be a better option here
-along those lines, if possible, get Di2; makes position adjustment (and you'll have quite a few of these) a lot easier
-don't skimp on the small stuff. I think I raced with shot derailleur pulleys for a year; probably stole 5-10 watts.
Good luck and have fun
PS. Hope you are wearing a N95 mask while doing the CF work