Not an LS1 guy but isnt the TB a little big for what done wouldnt you be losing some power there and honestly a tune never hurts.
car is put away
owner is out of town for the next 6-12 weeks …
plans for the turbo kit have started … 
Yeah, there’s no need for an 80mm TB, ported stockers are more than sufficient until you start making serious power.
Let me know if you want to check some things preturbo (or after) , I have a dyno to check things out on 585-865-1832 .
Hmm I doubt the throttle body has any negative effect on performance…My TB is a monster…my car has bolts on and it does just fine.