KZ750 twin valve spring diameter needed

Hey guys, I need to know the inner diameter of the inner valve spring on a KZ750 twin. I am trying to come up with a viton seal for this application and need this measurement to make sure there is no interference with the seal. Thanks to bountyhunter I already have the stem and upper guide sizes. I sell the blue viton valve seals on ebay and have gotten countless emails over the last few years about seals for this application. Thanks!