I picked up a header gasket for my 84 TA and while i was in the store the guy said it might be a good idea to soak the gasket in water for a couple seconds before i install it. I can see how the heat would help that gasket form a seam once it shrank from the heat. has anyone else done this? The brand of the gasket is Mr. Gasket. Thanks

Never done it myself but, I've heard of it many times. Generally, the water trick (as I've been told about) is referred to with a cheap, solid paper gasket, not a metal laminate gasket.
Personally, I like to smear a fine coat (just enough to glaze it) of ultra copper rtv on both sides of the gasket before installing it. With this method on about 6 pair of headers, I've yet to have a gasket blowout. Also, by keeping the sealer thin, it (rtv and gasket) won't stick to the head when the gasket is removed. Just something I do though...