I picked up a 1MM out of a 2000 western star am told it dropped a valve my ? is should I keep it and build it or sell and find a 6NZ what I was origanaly looking for its going into a 1986 ex hood 359 also I was told that only difference from a 7cz and a 1mm is the newer block could a guy just get a 6nz block that is lighter and better for leaks and swap the internals thanks