Is there a source that provides a barrel and bolt as a set which would eliminate the necessity of headspace issues during assembly?  I originally planned on using an upper assy., but now I think I'd rather piece it out but would like to eliminate any possible of having headspace issues, so thought there might be someone that offers a bolt with the bbl. that has already been ck'ed. for proper headspace.

Noveske does, DSG sells some of the combos

This ^^. But it's a match barrel and you're going to pay an arm and a leg for the set.  The liklihood of your headspace being out of tolerance is minimal with pretty much an new barrel and bolt you buy.

That's kind of what I thought, but figured if there was a way to remove any doubt, I'd go that route.  I was also thinking that I could just stop over to a shop that had a set of gauges and have them check it after assembly, just to be sure.  I just can't see investing in gauges for one rifle.  Yeah, I know, the solution would be to just build a few more and spread the cost out over more guns.  Hmmmmm......  I just remembered something, I have a box of headspace gauges from when I was in the business - I wonder if there is a .223/5.56 set in there.   The plot thickens.