What is the reason for changing the seals? Have you checked the valve guides for excessive wear, assuming you're dealing with abnormal oil consumption? It might be necessary to go to an umbrella seal, and forget about trying to use the original equipment type. The umbrella seal is much easier to install, since it can be slid down over the valve stem prior to installing the spring. Umbrella seals for exhaust valves are usually shaped differently than those for intakes. They are much shorter, sort of a disc without much of a lip that overlaps the guide. Since there is no vacuum in the exhaust port, it's a lot less likely to get much oil loss down an exhaust guide, at least until it gets extremely worn.
Jerry
