These valves are designed to be used with stock seats. 1.220 is stock exhaust size and 1.375 intake is a little larger than oem.  All is needed to open up the intake seat ID. Valves are made upon order and can take a few weeks. These valves are longer and are designed to work with our vanguard spring packages. Note always verify proper rocker arm geometry. Best to use our rocker arm spacer.