I am 6'8" and looking to buy a shotgun...how do I find the perfect fit?

Ever since I started shooting for sport a couple years ago, I have used my friends' shotguns. None of my friends even come close to matching me in size, and it has left me having to make some major compromises. I am now finally able to afford my own shotgun, and I am looking for some tips on how to find the perfect fit. I am aware that the people who work at the store I choose to buy from should be able to help, and that there are always gunsmiths I can pay a visit to...all I am looking for here are either some helpful starting points, or things to consider when making a decision. I am 6'8", 270 lbs, with a wingspan of 84" (7')...I am also left handed. Again, just any tips or pointers is all I'm looking for!