Following, I also have a 1940 Zephyr, serial 242xxx and it plays like a beast. Just overhauled. But I can't get the high end to play in tune, it's all so flat.
Yeah, that DV CHI looks like the right idea. I would rather not go with metal, and it would be nice if it was cheaper...I have a 269xxx Zephyr..... Ya, they take a little practice to pull them in tune (it took me a year or so of trying different MP's and practice). I settled in on Jody Jazz DV Chi. It is brightish and I can play the horn in tune with it. I also found an old King MO mouthpiece. I believe they were the mouthpiece that came with the series 3 or 4 Super 20. Its a little less bright but also plays in tune. They occasionally pop up on e-bay.
Out of curiosity, does your Zephyr have the rounded keys or are they squared?
This is the best advice. Like I said, it took me over a year to get used to the intonation on this horn. They don't play themselves like a modern sax will. You have to know where you are going and have the sound in your head before it comes out of your horn.I think if you have just picked up this saxophone, then you need to give it some time before deciding it's mouthpieces picky.
It takes everyone some time to get accustomed to a new horn and to adjust themselves to how it blows.