Trying in off course...treasure hunt for a bit

You can also continue to search on eBay, you’d be surprised what shows up there. Have you tried a much-easier-to find Waterford to see if it works?

Could the seller tell you where they found it?

The seller was a tack shop. I’ll continue to keep my eyes peeled.

Here is a Pessoa full cheek in a 5", in the UK though:
http://www.equestrian.com/p/bits/pessoa-full-cheek-snaffle-bit-with-copper-spheres/605802/