On HEMIs it is more important to have a centered rocker/valve tip pattern on the Intake side vs the exhaust side due to the more aggressive arc of the intake rocker (side loading of the stem). I have has success correcting rocker/valve tip aligmnet by moving the stands up or down. This requires opening the dowel locating holes so they can be moved. Typicaly I open them to .375 and use cam bushings to set and hold their position.