The Rhode Island Red is a popular barn yard family of chickens. You will find very few feathers on one of the roosters that has the dry fly quality we tiers of dries desire. Any color family of barn yards will do the job nicely. I suggest contacting some rural folks that may raise a few for eggs, etc. They may have surplus roosters you could purchase and turn into capes and saddles. 4 H clubs may be able to point you toward those that raise them Go for it! Part of the fun of tying is finding usable materials.
Most of our present day Genetics just did not exist back when many of our best patterns were developed. So what was used??
Roosters from many different colors of fighting chickens, whatever barn yard roosters local farmers had. Just remember, if you want dry fly quality hackle you will need to buy genetic hackle. (one of the browns will be the color of a Rhode Island red.)

Denny