well first things first
you have a v6 which means you most likely have a 2bbl intake
if you want to upgrade to a different aftermarket 2bbl carb
ill go ahead and tell you your wasting your time
do enough research on the 3.8l v6 and you'll understand that unless its a turbo engine
its crap
you can do all the mods you want
and yes you will gain some power
but in the end of the day
youv'e still got a v6 thats slow as hell
trust me i started in the same place you are in
your better off just doing a transplant to a better engine (350, 383, 454, 455, ect.)
but if your not up for the transplant heres a couple links ive found on the v6 to help you attempt to bolt on horsepower
but just remember before you go dumping everything in your pocket into the v6
horsepower doesnt bolt on
http://tech.oldsgmail.com/buick_mod.php
http://www.beforeblack.net/NAnotes.htm