At 11psi with 180k on your motor your motor will take a crap as soon as you get on the gas. Seriously. You need at least forged pistons (not necessarily rods) in order to get 11psi on your motor. You "could" do stock hypers but they wouldn't last long at all.
Either go with a h/c/i swap for the amount of money you would spend on a supercharger, and hope your stock internals will hold up, or get a forged shortblock, and then do the supercharger. I would do a lower mileage engine from a junkyard, and then do a split port h/c/i swap.
No offense to this site, but v6power.net has a bunch of tech info for v6 stangs. Kscoyote on here does a good job of tech stuff.