If the leash is tight and the dog is out front your are not in control. Constantly "Dog Paring him is not a good idea as it sounds like you don;t have control.
Or I'll say this is not a dog "I" would be taking to a Dog Park. Some dogs don't belong in a Dog Park. ,they can pick up bad habits and they can learn "you" don't matter!
He can easily kill a small dog and doesn't like Pitts? Well that can "work" it self out cause baring "responsible" ownership and handling most "Pitts" don't like other dogs!
This may prove useful:
Leerburg | How to Break Up a Dog Fight Without Getting Hurt!
Leerburg | Dog Parks: Why They Are A Bad Idea
Three Dogs Who Shouldn’t Be at the Dog Park or Daycare | Robin Bennett
And in this thread post * has some links on what you can do!
New Dog, Very Challenging