The problem with a color CRT in a compact (non-CC) case is the depth of the color tube itself. The color CRT in a CC is about half-again deeper (distance from the circuit board on the end of the neck of the tube to the front of the screen) than the monochrome CRT in a SE/30. (The CC's tube is also a 10" tube instead of the 9" tubes found in the monochrome compacts. So it won't fit that way either.)

To make a 9" color tube fit in a compact, you'd have to graft a 3-4" deep extension on the back of the case for the neck of the tube.

If you want color in an unmodified compact case, you'll need to use a LCD, and a board (like an LCIII+ or LC 475) that can be made to output the color video signal it requires. Luckily the LC sized boards, and the CC sized boards are the same width as an SE/30 board (and not too deep) so it'll easilly fit inside a monochrome compact case. (Actually SE/30s and earlier take less modification, because you have the whole depth of the case to work with. The Classic and CII had a big fan cowl that you'll have to remove to put in a different board.)

If you're going to go to all that trouble though you might as well just pop a recent MacMini in there and have a fully capable modern computer.