forget about your060->040ppc board , on a1200 you have the volt factor, i have no knowledge of any a1200 user who have done this and i guess thats because its not a good idea at all.
for cppc boards this is another story.
i think i have a link, let me see if i can find it for later.
btw, U sHOULD COOL IT , as your fpu will die if not , and if it does then you can scrap your card.
put cooling paste on the chip (under the sheild (YES MORE!) and put a big fan on the ppc sheild/rib , then you should also cool down your 68k, as this will get very hot aswell due to the memory issues and speed, even if you are still running it on 25mzh.
but do it properly and do it like the link says, anyway i warned you and dont come screaming on here if it dies all of a sudden.
good luck