I have four sets of 351c heads all 2v and was going to rebuild the two best ones. So can I do this,...take one good head from one block and another from a different block and combined them on one engine.Will this work?
one set is from a 71' and the other is a from a 70' block
Yea, you can, both should be the same castings. Have any been milled in the past? Or do you know? If you suspect they have, then have them cc'd to check chamber volumes.
There are half moon shaped indents around the perimeter of the block mounting surface of the heads. Those indents provide a good indication of whether a set of heads has been milled. Compare the depth of the indents on the various heads to make sure that they haven't been milled.