does anyone know if those cylinder heads by pro design are any good? with the o-ring, this would prolong the time between top end jobs right? also do they sell any for a 2001 cr250. if not, will one from a 2000 fit it? thanks.
Nope, the rings and piston are still going to wear and need replacing. The gasket would probably last forever, or far longer than you should ever go between top ends.