best carberator for the stock slant 6

Thanks for the info guys. Tthis is my first build so I'm ignorant of what to do and what works best. I've taken most of the stuff off the engine, and plan to pull it this week. I found a shop near buy that my friends recommend and was impressed with the owner he told me he would rebuild it for $1,300 and that seems very fair with a 3 year warranty I think. I would like some speed but don't know how to do it without having to change a bunch of stuff yet maintaining gas millage as this is my first time.