The heads I have are older aluminum type but were apparently good in their day. Better than stock anyway. They are Ford Motorsports M-6049-J302. I am new to the engine build thing and have a couple of basic questions. Q1 - These heads have been decked pretty much to their limit I think. If you were to put a ruler on the deck surface and slide it across it would contact the large valve ring which is sticking up past deck surface just a little. The cam I am thinking of using is a Comp 35-440-8 (Magnum 281HR) with lift @ .512. Do you think there will be piston to valve clearance issues??? Q2 - the heads have valve guide plates but I don't see any seals in their. Do all heads need valve guide seals when guide plates are used? Thanks for your help.