Shouldnt hav any trouble. I hav a 62mm TB and when I installed it I didnt do anything weird causing great concern.
ITs more like taking off a 2barrel carb and puting on a 4barel. Just more air, which you cars MAF should pick up on it and adjust things its self.
But a modification to the Pcm will alow you to tune it a bit, to get the max HP gains.
So you milling out the TB, or you doing it by hand with a die grinder? Just wondering.
The trick is geting the butterfly just right, Good Luck.