Few states have reasonable wild bird populations and Lord knows how many SD releases in a year...lol.
I don't judge a pheasant dog by preserve standards but many do, unfortunately.
IMHO, I would really consider a GSP. If you want an upland dog, there is no better breed.
I don't understand the problem. you have a dog that hunts within gun range flushes and retrieves birds and you are not happy with him? I have seen many people with the best pheasant dog ever that spend more time hunting the dog than hunting birds and watching birds flushing out of range and gone. I train mine to stay within shotgun range as I am nearing 60 I can't and will not run after a lab on a running pheasant. They sit to a whistle or else.
Best waterfowl dog I've ever had = Lab, Best upland dog I've ever had =Lab. Not to say they were the same dog, because they most determinately were not. The waterfowl-er, was too big to get into the ruff, ditches etc. and would wear out after a couple of hours in the upland field. The upland dog would get bored in the duck blind, and was too small to fight river current like the bigger dog. Best part was that both of them were passable at the other hunt type and could work well together. I don't think breed matters as much as a dog having the correct build, perseverance and personality required for the skill set. I ran a Rottweiler that was a good upland flusher, she was hard mouthed and a terrible retriever, but she did try, and was very remorseful for crushed birds, still she could find and put up the birds, she loves it and could run for hours.
With the possible exception of dynamite that comes in a little smaller package