If the inlet or exhaust valves are damaged, bent, or pitted, the performance will be down, with loss of compression, poor gas flow and unpleasant mechanical noise.
During the course of a rebuild, it is a better option to renew the old, worn and brittle valves along with these Valve Stem Seals, rather than trying to penny pinch and compromise the reliability and long term durability of your engine.
Why not order all the gaskets you require at the same time - save money on shipping costs with a multiple order. Try this gasket sealant: 08C70K0234M as used by the factory professionals.