I buy belts for my linisher from this (established, midlands-based), UK business via there Ebay shop – just checked and they have the size you asked for in Alox, Zirconia, Ceramic, and Silicon Carbide, in various grits 24 – 500.
I see that they will also make belts to size if required.
They use quality abrasive belting with a nice flat oblique join.
I don't have any connection with the company other than as a very satisfied customer.
https://www.ebay.co.uk/itm/402537117588?hash=item5db914f794:g:dHcAAOSww6lfpBvj
..hope the link works..