Something I've been thinking about.

[bgadow]

The closest I can think of in a color crt might be something like what was in the 15" hybrids of the late 60s/early 70s, but they are most certainly going to be way too deep to fit without mods. They would be more rounded than mid-70s tubes, but still not as round as what was used in the Predicta. If you were able to design and build a head from scratch, that might be the easiest thing to base it on.