I dunno...using 60-70 year old receivers and staking your safety on them?

Is there some way you could fit modern receivers into the earcup/receiver holders without destroying anything? And then replacing the old ones for display?

I have an AN-H-15 that I'm trying to retrofit with modern receivers. it's not easy as the AN-H receivers had provision for protecting the wire runs.

Also, I've seen pictures of an ANH-H-15 with a period correct boom mount for the mike. If such things were done to your helmet you might consider that. You can get Period booms and the mike might fit