One other thing that some suggest is to cut the entire rear window frame out as a solid piece, then weld it back in after the top is lowered. This allows you to use the stock glass and seal and keeps the original appearance of the rear window.

I have a recording of the Monstor Garage episode where they chopped and channeled a '54 Chevy. It shows some decent sequences of them bracing the body, removing the top, welding in a new roof section and also a new rear cowl. Not sure how much of it would transfer to your project but I would be happy to make a copy and send it to you.

I also ditto the advise on Tex Smith's book(s). I think your practice idea is a great one.

Good luck!

Pat