LOLyou're going to be pouring a lot of money into your lil 6'er if you want to smoke a GT. Are you wanting to beat modified GT's or stock?
any power adder he puts on there will smoke a factory GT. and if it's a turbo or centrifical it will smoke modded N/A GT's. the 3v GT's are the exception.
Personally if you are mechanically savy get a turbo kit. If not so much, get a centrifical.
Your internals are good til 350rwhp with a good tune. so if you get a turbo the 330rwhp range is a good safe place. With this power though you'll need T-lock for traction, subframe connectors for frame, and fuel mods like fuel pump and injectors to feed the power.