FlyEng, Looking Good, MAN!!

It took me a minute to see how you did the firewall mount for the back ring, but then I saw what you meant by having to watch the bolt length since they will be coming from behind the firewall. It will be a little tricky to align and install, but it's something you have to do only one time. Once you're happy with the position, perhaps use red Loctite and you won't have to touch it again.

When you have a chance, it would be nice to see some pictures of how you did your spacer rings. I have been thinking of alternate ways to do that.

Good job!