I have 2 sets for GMC's, NOS in the boxes. The high lift was done by short sideing the push rod side. The stock push rods "may" not rub in the holes but 5/16" or 3/8" need clearance work on the head. If you put these on a a roller cam with the higher valve spring tension needed the rocker could fail a lot easier than use them on a very mild street application. They are very light and use the stock adjusters....Good Luck

216.158 MPH 12-Port 302 GMC on 70% 171.0 MPH 302 stock head on gasoline 7 years later