I put new valve locks/keepers on mine when I did them. I always do that when I rebuild a set of heads. 20-30 bucks. Not all do this, it's up to you. I have seen results of a broken keeper. Not on a 7.3, but still.. I got some on ebay from a seller named falcon? I think.
On my heads I ended up with .045 shims iirc on each one. The actual installed height and seat pressure I don't remember for sure, and didn't write it down.