You can solo hell act 5 at prolly low 80's with the right class and gear.
I know I've duo'd it at ~80, maybe even less. Baal is a nightmare when you're playing straight legit though, no twinked out gear, no uber 99s to help you, it's so much harder.
Yea, my 82 zon had to port back to town a lot since she kept running out of arrows and pots, kill prolly took somewhere around 10 minutes. Have some decent gear, but nothing that really helped me out a ton.