You can go so far as to use a whole setup for the 98+ throttle body, but because of the added bore and different MAF sensor you will need to adjust the MAF tables. The air velocity will be much different, and there will be more air going in than the sensor will pick up. I do these as well, while still using the old MAF sensor, but it's just down right easier and more cost effective to use a newer TB and reprogram the PCM.