I've gotten through normal heroics with some pretty low end of the gear spectrum healers on me while tanking as ret. I generally wear mostly relentless pvp gear for the Stam + crit reduction. I fill in with some expertise pieces here and there and make sure I'm hit capped as well. I use royal Seal of King Llane and Juggernaught's Vitality for an extra chunk of stamina to provide some HP to soak damage and some extra cooldowns to use. I have around 33k HP buffed with just kings.
Threat is easy so you can focus on keeping Sacred Shield up, and using your art of war procs to make the healers life easier.
Made it through new heroics using this strategy with pug healers and its a challenge and pretty damn fun.