Good Man!
I have found out from painful experience that there is a reason that a lot of NOS parts are still NOS.
They were likely found to be NFG years ago and just put back on the shelf instead of being chucked out.
I was thrilled to find an NOS ZA-Magnette speedometer only to have it break a speedo cable because it was seized.
To add insult to injury I assumed that the old cable was at fault rather than the NOS speedo and wrecked a second one before I caught on!