Hey, hey now.. Who's knockin' Snake's outfit?
I'd wear a stealth suit in an instant... I wish I could get the nano-machines to go with it tho
Closest thing to it would be a divers suit, but instead of maintaining an optimal body temperature (as per Snake's survival suit), a divers suit will just retain heat (you'll die, people will laugh)
As for the rest of his gear (vests, holsters, etc), dunno - either made up by Hideo Kojima, or has real counterparts, but you'll likely find better answers by searching for that on the big-wide intar-web.
I know if you have a FaMas, and a Mk.23 w/ LAM & suppressor, you've got his weapons...