It looks like the end links the boutique recommended for the 1590 bracelet are the 867 vs 831 end links you mention.
The eBay auction says the bracelet came off the Planet Ocean 232.90.46.21.03.001, but the auction doesn't mention any model or end link numbers. However, it is clearly the braceletet for the 45.5mm Planet Ocean in Titanium.
From Omega website the model watch that eBay refers to is this
https://www.omegawatches.com/en-us/...an-600m-omega-co-axial-45-5-mm-23290462103001Click to expand...