Not quite sure why you are having problems finding feathers, because most strung saddle hackle I find in the shops these days will tie those sizes. If you are looking for a bit fancier, Whiting schlappen might be useful, although my shop does not carry chartreuse so I do not know how readily available it is. Bill Keough has the best WB saddles in my opinion, and you should be able to find a good saddle if you look around a bit, but everything seems harder to find since the feather craze...