The 440 source heads are good pieces. I would never buy complete heads from anyone of the manufacturers. If you do buy a complete set then take them apart, clean them, check valve guide clearance, valve job, and then replace the junk retainers and keepers. I would also have them pressure checked for casting flaws and check the deck for a good flat surface. All of the head manufacturers have these problems, none of them are truly bolt on and if you have found someone who has good luck out of the box then they should go play the lottery.