Now that is very interesting.
A MacTV is, as I understand matters, just an LC520 with a TV tuner card (and black plastics). The LC520 became the LC550, which is a much improved machine.
I have an LC550 logic board in my CC, which now reports itself as a Color Classic II. It definitely has the vram to do 640x480 quite happily (256k more than a genuine CCII logic board), and is overall a very spiffy Compact Mac, with 33 MHz 68030 and bus, LCPDS ethernet, and RAM capacity in principle up to 128MB (the 36MB in mine, however, is more than enough). I prefer this to the LC575 "Mystic" configuration, as it seems much more meant. A 68030 is a perfectly capable processor when running on a decent logic board design (whereas the LC575 is most likely running its 68LC040 on a logic board essentially designed for a 68030).
I will go and fire up the CC-LC550 again tonight in order to see if it will do 640x480 resolution, but I don't think it will. I wonder, however, if a simple ResEdit hack is possible?
What does a CC with MacTV logic board identify itself as being? A Macintosh TV?