Wow, that's quite the torso! According to the Backcountry sizing charts, the large fits up to a 22.5" torso. The XL is a bit larger than that I'd imagine, which you'd certainly need.
It's a bit tough to provide specific guidance without knowing how much you plan on carrying in weight and size (tents, sleeping bags, etc. can vary greatly in how much they weight and how much pack room they take up)).
Generally, though, the Argon 70 should carry everything you need. It's often considered the most feature-rich and comfortable of Osprey's packs, although a bit heavy. If you're up for carrying the extra weight, it's a good choice. If not, I might recommend going with the Osprey Aether, which I have. It has a few less features and a slightly less padded hip belt, but it'll carry decent loads and is very comfortable. If you plan on carrying 50+ pounds of gear, go with the Argon. Otherwise, I'd recommend the Aether.
Either way, I'd order the XL from Backcountry, REI or another similar company that has a good return policy in the event it doesn't fit.
If you have any other more specific questions let us know.
Good luck - getting back into backpacking is a ton of fun!