New .30 barrel...

[PRD1]

My post WW1 .30 rebuild shooter would benefit from a new barrel, I think - the original bore is pretty rough, and, though it shoots well, it would not be happy with cast bullets, and the headspace is a bit long.
Problem is, finding a new-condition barrel in .30. SARCO currently lists new, late-production .30 barrels in the white, but I'm not sure that they are fully interchangeable in original production arms.
I would be willing to install the barrel myself - I have the proper tools and experience, but would have to acquire a chamber reamer and, if available, headspace gauge.
On the other hand, I'm not averse to handing the job off to someone who does this as a regular thing, if a new-condition barrel is available, and the wait time isn't geological (I know how custom gunsmithing works, having been there, myself).
And, in a related vein, where might I find proper FMJ bullets for the .30 Luger? I have a dwindling supply of Lapua bullets, but can't find anything of the correct weight and diameter currently available.
Any guidance and help appreciated!

PRD1 - mhb - MIke