I'm a little late on this but I hunt my pointing lab in similar events, you need to pick a dog that suits your life style and hunting style, these events are ever other weekend or so after season, train it and go compete.
We consistently run faster times than GSP's, English pointers etc.
it's a crap shoot, there is so many factors that play into these "runs" you could run in the middle of the day when the wind is blowing 15+ and scenting is poor vs the guy who runs after someone that leaves 2 birds in the field and now there's extra birds for the following run...
You could have a stellar run and have a safety happy hunter that can't stop the clock without yelling safety at every other bird and they beat your best but only shoot one bird.
The best advice I received this year from a guy who's been playing for 20+ years is to just go out and have fun with your dog, don't get mad if you have a bad run, just come back each run is like a new day! there's to many variables in this game.
Remember it's as important to be a great shot also, misses will kill a run quicker than a slow dog.
If you're set on a GSP I can pm you the top feeders in the pointer division in the 2 series we run. This is what they are bred for, tournament hunting.