I just got my car and it had a 305tbi, I was wondering if I got a 350tbi out of a k1500 or something will it be "plug n' play?"

Pretty much, yea.... depends what you mean by 'plug n play' though.

Meaning I don't have to do like any re-wiring? What will I have to do other than swap it in and plug back in all the electrical stuff?

tune up and bigger injectors is all i know

Bigger injectors than what comes with the 350? What kind of power does the 350 have? I read its only like 210hp?

more than likely still better than the 305!!

The only difference between a 305 TBI and 350 TBI is the size of the injectors.. Everything on the Throttle Body is the same besides the injectors.

no, I think he is thinking you dont have a TB with the engine.

I have no motor! None what so ever. I was refering to the complete 350 tbi as opposed to the 305 that was in the car, not just the injection system.

The only difference between the 305 and 350, as far as the computer goes, is the knock sensor and (possibly) the injectors. If you have the proper parts for a 350" mill, then your set.