youve just named my number one pet peeve . customers who say they have(machine shops too) magnafluxed (crack checked) heads only for me to find them (cracks)after porting for 20 hours or so. who gets to pay for that? me thats who! its bs! not a big deal if fixable but most are not. problem is that most cast or aluminum heads that have been used get fatiqued from heating and cooling. so if your going magnum i suggest iron ram heads ,you can get them at hughes engines bare for around 600 pair there beefy have lots of room for porting. flow great out of the box. smoke r/t heads on the flow bench, somewhat cheap. and did i mention there new? no cracks ,come in either bolt pattern magnum or standard la. hoooooraaahh