You can add Galleon to the list of faceroll bosses
Horridon is probably doable at 617 ilevel, however it requires good execution - and in my experience it's hard to execute a fight properly on a class that you're not comfortable with. I would recommend more gear, 630+ to make it doable fairly easily, and 640+ to make it utter faceroll.
Ji-Kun is similar to Horridon in difficulty, maybe a bit easier.
Sha of Anger would be difficult to pull off at ~630. The DPS requirement is only 8k or so, however you need to frequently run far out of range to avoid being MCed. However, I can never actually get a proper attempt solo, as other people invariably show up to help, which makes the DPS requirement vanish.
Oondasta requires 650-660+ gear. This should be easy to get on an alt in 6.1.