If you have a good thermometer, measure the idle and busy temperatures of the CPU before you replace. I got a few m68040s which were supposed to be the newest mask which got just as hot as an old early 1990s mask before I finally got a real new one.
Got me one of these also. USD43. Startup is a a few seconds quicker. Also I notice the fan turns itself on and off now, whereas with the 68LC040 it was on all the time... That´s cool