It does seem like a bit of a stretch. Currently my item level is 362 and I have the applicable mastery gems in every slot(parry/mastery, mastery/stamina and pure mastery) gear is reforged to mastery and with a mastery elixir and food I am sitting at around 99% combat table coverage(dodge + parry + block) with raid buffs.
here is my armoury: http://eu.battle.net/wow/en/characte...oterick/simple