Nice 342!
And a lot of fun to bring back to life.
I still have a brass valve body for you if you want; send me a pm and I am happy to post to you foc.
I've tried to use an inlet seal carrier with "post" in the middle in a gun that had an older type inlet seal carrier without that post.
It didn't work. I think the inlet seal seat is different for both types. But perhaps you will get better results.
Sheridan and Benjamin used both types. They have exactly the same configurations.
I highly recommend Lawrie for resealing the old valve and inlet seal carrier without hole in the middle if you come to the conclusion that that is necessary at some point.
Btw I received hammer springs with power adjusters from Ped recently. Super cool. Will start to experiment with those soon!