I know this question has been asked in different ways but I thought I would try again. I have a 1999 yz400f with a damaged head. I am looking at a 2002 yz426f head on ebay to replace it. Looking at part numbers, it is obvious they are not the same part but I have been told that the only difference between the two motors is the stroke increasing the displacement. Everything else is the same. Would it be a mistake to purchase this head or am I good to go?