I am look for suggestions about a good accurate varmint upper that can handle larger grain bullets.
Thanks

Try a 1x9 or 1x8" twist barreled varmint rig. That will handle up to 70grs or so,with the 1x8" barrels handling 75gr SMK.
Lots of folks sell them. Lower priced uppers are available from model1sales, M&A and JT Distributing among others. There are middle priced options available from Rock River Arms,Bushmaster,etc.

What kind of accuracy does the RRA uppers from ADCO offer.  Will they shoot and 80 grain bullet
well.

I was looking to have an AR-15 varminiter as a back up to my 22-250 bolt gun on PD hunts in SD. I have had experience with a Wilson SS bull barrel and the Bushmaster varminiter. Tried many different powders, bullet styles and weights. My best groups were in the 1 1/4" range at 100 yards off sandbags.
Obviously, niether lived up to my expectations, both were sold. You can get a lot more for your $ going with a bolt gun.

My experience goes against the other poster.
I bought a 16" stainless fluted bull barrel upper from J&T.  1-8 twist.  I've never shot expensive ammo with it.  I've always bought Winchester 45 gr JHP.  I typically shoot 1" 3 shot groups (I haven't shot it from a bench much)  But, the thing that opens my groups up is usually a flyer.  I blame the flyer on me.  If I could pull that in, I think it'd be around 1/2" with ammo that J&T says will suck in this upper.  I also haven't shot groups since I did the 15 minute trigger job.  I plan to shoot some this weekend, maybe I'll scan some groups.
If this is for prairie dogs, I'd look for a longer barrel, 20"-24", assuming that you won't be walking too much.  If you're going to be walking alot with it, I'd recommend a lighter barrel.  Either a 16" bull (fluting optional) or HBAR or something like that.