I once tried boost an A1000 by putting in a 16MHz 68000 and soldering a 14MHz clock signal from the custom chips.
Didn't work oddly enough (the CPU and chip set are very closely coupled so it'd never work, but I didn't know that then...).
So I put back the 68010 and it worked fine :-)
Heh, I was doing overclocking back in the 80's!