Will 3/8th nipple overly restrict gorton #2 vents?

My two (single pipe, parallel flow) steam mains are each vented by a single Gorton D. The vents are located in the elbows at the end of each of the mains, where they turn down to the wet returns. The cast elbows have a one-inch tapping with a 3/8th reducer bushing, which in turn have a second bushing to reduce to the 1/8th size of the D vents.

My plan was to pull out the bushings, replace each with a nipple of one inch pipe, then transition to an antler with two Gorton #2s per main (each is about 35' of two inch pipe).

So far, I have been unable to crack the large hex bushings free.

So: if I left the large bushings in place and used a 3/8ths nipple, would that "bottle neck" reduce the #2's capacity excessively? I can try to cut the bushings out but if that can be avoided...

The pressuretrol is set to cut-in at 0.5 and out at 1.5. Thanks!