90 kdx200 forks vs 02 220kdx forks

Hi Im new to the forum and was looking for a little info on some forks.I just aquired my first kdx, a 90 kdx 200 which was in poor shape.Ive been rebuilding the bike just to do some trail riding.Iwas wondering the difference between the 90 kdx200 forks and a new set from a 220.would it be worth a swap.A good friend of mine is willing to sell me his forks as he changed the forks on his bike.Is there a huge bifference between years with front forks?Can you feel a big difference in the way they ride?Also I found that there is a hairline crack in the cylinder,right in front of the main exhaust valve,is this common to these bikes?And what do I do with it,sleave it or leave it alone?Thanks for any help you can throw my way would be great.