While conservative wisdom would suggest that you are pushing the envelope, I say go for it. Just know your risks, as you obviously do. The hobby isnt advanced by people who play it safe.
[puts on fire resistant suit] My tank is similar in size (72x28x30), and I plan to have 6 tangs (yellow, vlamingi, hippo, tomini, sailfin, naso, kole, and powder blue) in it in addition to 2 clowns, diamond goby, 2 firefish, filefish, flame angel, cowfish, niger trigger, bluethroat trigger, longnose haw, sixline, chromis, copperband, bangaii, and a pajama cardinal. I'm going to add fish slowly until I hit water quality or temperment issues.
Look at a lot of "experts" tanks online. They're packed with fish.