I've over-clocked my 25 MHz A3000 to 30 MHz and (even 32 MHz for short periods of time) and the SMD 030 over-heated quite easily but was never burned out. The one thing I did do was change the 1K address/data bus pull-up resistors to 3.3K. It's a fair amount of work to do this but this A3000 design bug will probably limit 030 based over-clocking to 28 MHz.
