KBP.... what is the intended use ?
IE ... collapsible stock ?
What barrel length looks like what you'd like ?
General use but pretty good accuracy ?
Coyote hunting ? So a variety of distances, and you might be carrying it ( weight wise ) ?
What ammo would you typically use ? Bulk FMJ ? ( usually not very accurate ) Decent accuracy ammo ? ) 15 bucks a box )... or match ish ammo ?
I'd suggest you assm. your lower ( can be readily assm. with no specialized tools, except the possible castle nut wrench ( carbine stock wise ) ... and then buy a better barreled complete upper. And even then ... your first choice might be OOS.
White Oak has an excellent, well respected reputation...
https://www.whiteoakarmament.com/sho...ck-uppers.html