Bunsen: yes. Back in the days of an active CC mod community, people did cut down 5xx boards and stuff them into CCs to avoid the hi-Rez hack. There were a few non trivial circuits and components that had to be moved/patched in order to get it to fit. All in all it wound up being as much work as the various Rez hacks, and crippled another Mac in the process.

Of course, if you're just stuffing Macs into CCs, you could find a 10" 4:3 hi-rez monitor and the most recent Mac mini and have the most powerful CC in the world!