nrracing does sell gaskets for the greyhound. when you go to there site you need to look up under stock oem parts and they will sell you the better ss narrow stem flowing valves 25/24
http://www.nrracing.com/category-s/1843.htm?searching=Y&sort=13&cat=1843&show=30&page=1
http://www.nrracing.com/category-s/1843.htm?searching=Y&sort=13&cat=1843&show=30&page=1