KMC not much to offer with those diameters.
See link below of what is in our system.
With the call out of “niche”
You are probably looking at a custom part number which usually have lead times and minimums to order.
But first you would have to pick a manufacture and a series and ask the manufacture for a customer or build a part number.
Then you can see if Digi-Key can do what is called a non-catalog request.
which is explained in this link below from Robert Fay
If you are looking for a part from one of Digi-Key’s Suppliers that is not listed on the website it may be possible to order this part for you. Digi-Key will quote items that we do not currently offer as long as it is from a manufacturer that we carry and the manufacture will make the part(not obsolete etc). This would be what we call a non-catalog quote. These quotes generally take from 3-5 business days to back from the manufacturer. A non-catalog quote will come from the manufacturer with pricing, lead time, and minimum order quantity if required. If you would like to request a non-catalog quote please contact our sales department at sales@digikey.com and let them know the part number and manufacturer that you are looking to order.