For that bullet weight range, I would want at least a 1:8 twist. 75gr and 77gr pills run great out of a 8-twist barrel at mag-lengths in my experience. Now...generally speaking, a 1:8 twist will work ok with 80gr bullets, BUT 80gr class bullets in an AR will be single-feed ONLY and you may ultimately want a slightly faster twist to get the most out of the longer, heavier pills if you really want to go that route.
As for your rifle options bw the SASS and TPR...I would expand your horizons and ditch the TPR. The mini-SASS is a nice platform, offers several "upgrades" versus many off-the-shelf factory rifles and won't break the bank. That said, depending on your total budget, the features you want/need in your rifle, etc., you should also look at RRA (the Varmint A4, Predator Pursuit and R3 Comp rifles...just got to try one of the R3's last week...are outstanding, all 1:8 twist, all easily sub-MOA rifles in capable hands with proper ammo).
ETA: Ooops. elfster beat me to the punch on some of the RRA recommendations, but they are excellent rifles to consider...again...as long as they generally meet your basic requirements in an AR. I have had nothing but faithful, accurate services from every RRA factory rifle I've owned and elfsters own shoot out results speak for themselves with respect to the accuracy end of the spectrum. No comment on shooting from the "sissy bag."
(Joking...just joking!!!)
