You're going to find literally nobody uses the HLA retaining clips. They don't normally fall out by themselves and every man and his mighty max (or woman in order to keep the SJW's at bay) would've removed the rocker rails and cam caps without them at some point. If you are concerned that the HLA's could fall out, buy a pair of rubber gloves and cut the fingertips off them, then stretch the glove fingers over the ends of the rocker arms. The general consensus with any assembled head is - go over it and check everything. Valve play, leak down test, deck face - anything that would cause a compression leak or any other kind of leak. I've heard enough stories of the V8 guys buying performance heads only to have valve float and compression leak problems straight out of the box without checking them over. If your recon'd head hasn't actually 'failed' I would use it, but I would never mill a warped head to true it up. Just asking for trouble IMO. Messes with compression from chamber to chamber, could load up the cam bearing faces from the cam bed no longer being true (and cause them to wear out or seize the cam *this causes cam breakages as seen in the 2.4 engines). A pro shop will put the head through an oven, get it up to temp and put it through a press first, then skim the face.