Does AA offer an upper with a Satern barrel? They used to.
Satern makes great barrels, some of the best and I have one that's my most accurate rifle period, .33MOA consistently. It's uncanny. HOWEVER, I custom ordered that barrel and it took 'em over two years to ship it out. Another one I ordered never materialized. IF they have one in stock that suits your needs, get it. If not, well, they claim they do custom orders but they really don't. Some 6.5 bullets have a more aggressive ogive and that can impact the rifling with certain loads. I have an older chambering. But I knew Bill A. some back in the day and turned me on to 120gr. Nosler BT's and I tweaked the handloads and that was the magic recipe. 95 or 100gr. V or AMAX bullets (I forget but I think the VMAX) actually impacted rifling pretty bad at recommended length. Not the 120's, smoother, less aggressive ogive I guess, so bullets can matter in these sometimes.
Lilja makes a good one, best button rife you can get. Does Krieger make one? If so I'd be cut rifled and I'd be inclined to think theirs would also be top grade.
For complete uppers I wish I could give you more advice but I assemble my own here. I'd look for a cut rifle barrel if possible and accuracy is a thing, and a JP Ent. FMOS BCG will be impossible to beat if you need a BCG for this, nothing is more reliable. AA makes an improved bolt too. If you're a vet or disabled vet or active duty, mention that, most of these places will offer discounts to certain persons with bona fides.