I've been playing several characters in Diablo 3, but my first and furthest along is my barbarian. Recently, a friend (monk) and I have started making key-runs in order to craft the Hellfire Ring. Although I don't die as often as he does (barely) playing at elevated monster power, he does a ton more damage than I do. I'm doing around 27k damage. After some googling around, it appears that I could get more damage out of this fella, but I can't find anything that actually shows a good average damage for a 60+ barbarian, just lots of "look at my barbarian he did 6-bajillion DPS against Azmodan" type posts. Does anyone have any knowledge or resources for this?
Check DiabloProgress. You're asking for an end game barb, so compare to the world number 1.
The stats you should get: Minimum 1000dps weapon with a socket. Minimum of 2.3 attacks per second. At least 45% critical hit chance. Critical hit damage. Around 2k strength. 8-10k armour. 600 AR
A solid benchmark for farming MP10 in patch 1.0.8 with a spin-to-win barbarian is 170k unbuffed DPS with 650k EHP. You can use a tool like d3up to help calculate these values and help determine the efficacy of potential item upgrades.
A more generally applicable rule of thumb for efficient xp/legendary farming is that you should be able to kill trash mobs in 3-5 seconds and elites in under 45 seconds while dieing to less than 1 in 5 elite packs. Pick the monster power where this holds true for your character. For ubers, you'll want to do the highest MP that you can successfully complete.
As far as improving your character's damage, my advice would be to move your focus away from legendary items and focus on stats alone. This spreadsheet is a great list of what stats to look for in which slots. You certainly won't be able to afford items with the values listed but you can use it to focus on the appropriate stats for each slot and get the most for your money.
For example, the amulet slot has great DPS potential (high crit chance and crit damage caps) while pants have great EHP potential (high AR and vit caps + slots). In your case, your pants are more DPS focused while your amulet is more EHP focused. If you were to swap the focus on these slots you could, fairly cheaply, increase both your DPS and EHP.
Stack crit chance and crit damage on most of your items. You want a 1:10 ratio for crit chance to damage. For example, 45% crit chance =/= 450% crit damage.
Also, you should get a lot of vitality on your items. Do not worry too much about strength, but try to get a 1:3 ratio for strength to vitality, as in 50 strength and 150 vitality. My barb at level 60 with no paragon is around 250k dps unbuffed. Fully buffed with wob and br and punish rune in bash, I hover around 470-480k.