The IDE-based boards like the 630 will not swap into a CC variant (or indeed any other AIO models except a 58x). For that, you'll need to do the Takky mod. While you can basically run the Takky mod off of the stock CC analog board, it's not recommended: the 68040 draws more power than the 68030, which is stressful enough; adding a high-res mod and expansion cards (let alone a DOS card) could cause stability and longevity concerns. Usually major mods like that use an analog board from a 5xx because they're already set to run high-res and can put out a bit more power. They need to be physically cut down, though, because they're too wide to fit in a CC chassis as-is. It's major surgery but props if you can do it.Long-term project is an attempt at cramming a DOS-compatible board from a Performa 630 into a Mystic '040. I know it's missing the video port on the motherboard, but... I feel like there's a way this can be done without actually doing a full Takky mod. Everything else is there... it just feels so possible. Maybe someone has already done it? I couldn't find anything online. I've already got a Performa 630 DOS-compatible motherboard ready (purchased on eBay a couple of years ago when I first thought about giving this a try). Feels like a good project to take on.
Does the 630 DOS card fit in a 575 logic board? That may be interesting if it does. Also it would swap directly into a CC without a Takky mod, though you'd still need to do something about the resolution (either high-res mod or ResEdit hack). I'd still be concerned about the power draw of the DOS card; the 486 wasn't known to be a low-power chip.