We have been porting out the factory inlet bells for years. Problem is as you well know that the seals are worn. (We do sell these new as well) the ring that seals the seal also have a tendency to chip or break upon installation or removal. What we have built is a billet unit that is ported beyond what we normally take the stock units to because of the strength. The factory unit is just a pot metal unit.
Our new unit comes fully polished with new o-rings. Great performance upgrade & a great way to get a better seal & increased air flow.
The factory unit (GM part # 25515938 ) has been discontinued for years. So if your missing one or yours is just plain worn out or broken this may be something you can use.