I don't believe, at this stage in the game, it's feasible to heal a random tank through heroics with 4x ret palys (I assume what you're asking). Even if 4xWoG could keep up with average dmg intake (which I don't believe it would), there is just a ton of different healing mechanics that you'd be ill-equipped to handle.

Maybe this will change with gear, and I could be wrong since I haven't actually tried. Just thought I'd give you my impression from having a semi-geared retribution paladin at the moment.