You can tune any instrument to any arbitrary frequency for center-c and as long as all the notes are of the same relative difference between them the melodies will generally work and harmonize. As long as all the instruments are synced it will sound ok in a band too.
In modern day we have a definition of what frequency center C is. But I have to wonder, how do we know the modern day frequency for middle-C is anywhere near the frequency used historically. In fact, when even was the idea solidified at all?
@antares The bell approach makes a **lot** of sense. that said bells can presumably be tuned by grinding,and i assume that is how they are fine tuned after the initial casting. But yea your point that once tuned they tend to remain fixed and cant be tuned without modifying the instrument makes a lot of sense.
Thanks for a wonderful response, lots of good info here.