If I inderstand you correctly, you want to use a LS2-style TB in a gen 3 engine.
You will not get reliable operation from a new TB without TAC module in a Gen 3 PCM, they are a different design and use different sensors and controls. I have made them work using adapter boxes but it makes the swap expensive.
Just find a 05-06 TB with a matched TAC and it will work very good. A mechanical TB is a good option if you don't care about cruise control.