Even if all the electronic problems could be successfully solved, (the 15GP22 is 45 degree deflection and electrostatic convergence), very serious mechanical and aesthetic problems exist.
The large bezel visible from the front is *not* flat on the backside as are most bezels, there is a circular lip, about 3 inches deep and about 16 inches in diameter that is designed to support and insulate the ultor ring of the 15GP22. One would have to remove significant portions of the lip to install a rectangular jug or (gulp) a flat panel.
Aesthetically, it would be difficult to make the conversion look like the original...remember, the 15GP22 was produced before the process to deposit the phosphor dots on the curved inner surface of the faceplate panel was developed. What is seen from the front is a flat piece of glass with the phosphor dots deposited on it (screenprinted???)... this screen is mounted behind a metal bezel, and the whole assembly is supported *inside* the 15 inch glass faceplate panel, giving that unique appearance. Perhaps something like a porta-pottie jug behind a wooden bezel placed inside a glass 15 inch panel could replicate that appearance fairly well, but where would you get the panel? IMHO, the ugly *black eye* of a flat panel would not be a good choice, a real CRT would be much more appropriate.
I must admit that one time when the chassis was out of my set, I did slide a 9 inch Trinitron in and "enjoyed" the view for a few minutes
but would never consider a retrofit, mostly for aesthetic reasions. The CT-100 is enjoyed for what it is/was, it does not have to produce a picture to earn its keep.
my 2 cents,
jr