My name is Frank the Tank!

I need a rescue for a stray we found in our neighborhood back in August. We have been fostering an 18-month-old, 80-lb pit mix, Frank the Tank. We got his first set of vaccinations and his rabies vax
Positives about Frank:
He is house and crate-trained. He can use a doggy door. He is a big, gentle goofball. He gets along with people and kids. He loves bones.
He knows commands like drop it, sit, and kennel. He likes all other dogs and is playful at dog parks.
Negatives
My two older dogs do not like his playfulness. He is quite energetic and needs a place to run or frequent walks.
He has to be watched all of the time or he will chew items like shoes. He is heartworm-positive.
My older Pointer is the aggressor and Frank thinks he is playing but they end up fighting. We try to keep them separated as much as possible but I;m afraid one will get seriously hurt. I need a rescue to help us find him a new home where no pup will get hurt. Frank is a good goofy boy and deserves the best.