Rather than hunting around the junkyards to find a 5.0 block, cleaning it out and having to get it sonic tested, I'm tempted to buy a new 5.0 block from Summit. My friend says I'll do better with cylinder head fitment, etc., if I use a used, reconditioned block. He says used blocks are "seasoned" and mating surfaces won't warp from the heat. Is that true or a myth?