Hi! I would absolutely recommend a harness as soon as you can find one to fit him that is strong enough. My two are the same way - they pull like crazy when they want to get to someone! Otherwise, I am pulling them! But always on harness, with a "decorative" collar with ID on it.
I heard a terrible story when I didn't have my pups yet, and we were waiting for the litter. I ran into two gorgeous bullies in Niagara-on-the-Lake, and we stopped to talk with them. They were wearing the Kong harnesses (the kind I own now) and I asked about them, I had never seen such awesome harnesses. They told me a sad sad story about how they had 3 EBs: one of their girls had recently died from a collapsed esophagus from the leash/collar and her pulling. A total freak accident.
I was so upset for them.
I have since read tons on how bullies should only be on harness.
Anyway, that is my two cents! Good luck with your little body-builder!!!