Hmmm... Well, in theory (and provided every single part can run at the new speed and there are no noise issues) it should work at a higher speed. This would mean though that anything synchronised such as the native graphics timings, sound timings, drive timings, clock, floppy access, basically anything run from the custom chips might have issues. Increasing the graphics output for example will not display on some monitors as the syncs will all be quicker... Not worth the risk and effort I'd have said!
