I used to ride and made my own shirts. That was over 50 years ago and the shirts are history. I don't like the modern ones at all. Some of them are merely one color on the right side and another on the left side, no fashion at all. Sad...
Since I couldn't afford the real ones then, I decided to make myself pants and shirts, so did it the easy way. Bought 2 men's shirts that fit nicely in denim color. Put in darts to match my body with a little ease.
Made from one shirt the fancy saws and half circles, etc that goes down the front of the buttons on each side. Then sewed the back and front fancy part over and covering the shoulder part with a satin stitch that matched the color of the shirt. Then cut off the bottom, original piece, leaving the new part as the decoration. At that time most men's Western shirts had pearl snaps so that made them prettier. I had more than one pair of pants the same color so did the same with them after taking off the belt, then replacing it.
H Bar C is the brand on one of the old ones in a drawer. Can't wear it now, used to have an hour glass figure but the sand shifted a lot in the years since then. I think that H -C is still in business.