What are good barrel saddles for thoroughbred built horses?

I have a quarter horse gelding that has alot of racing bloodlines and built alot like a thoroughbred. He is narrow with a good wither and ALOT of shoulder. I have a Marlene McCrae saddle now but it seems to be sitting all on his shoulders instead of on his back and withers. I think it is pinching him when he brings his shoulder back.. any suggestions??