I picked up the exact same heads at a salvage yard for 50.00 I ended up dumping them for a set of 2.02's . The money I was going to spend for trying to make the valve's bigger wasn't worth it I was told .Try to find a set of heads with 2.02,s it will make a big difference . I am a firm believer of screw in stud's and guide plate's .Bare casting's from World Product's are around $ 287.00 each, these are excellent!!!