Halti's are Great but they are only a Temporay Fix to the problem. also if your dog has a neck injury which I think you said it's not always a good Idea to keep Having the dog turn his head which can also do some damage.
As for Getting a Chain Leash that can be dangerous, as if it gets wrapped around your hand it could cause some Serious Damage, I would Suggest a Good Cotton Leash, They even make them in handler Leashes with a Second loop Closer to the Dog so you can Reel him in a bit. Leather is a good collar, but Really isn't made for walking. Even in horses they have What are called Break-away halters and they are made of Leather or have a small leather piece that breaks when tension is put on it so they don't hut themselves, so a Good Cotton Collar and Leash would Be a Good Bet.
Treats are always good if your dog is food motivated. if he's pulling I would just stop walking and wait until the leash is Slacked before I would Start moving, Relaying the message that if you pull we aren't going to go anywhere. also make sure to make him sit at corners (more of a Safety thing) it helped my dogs learn that they weren't to go in the Street. if he's pulling You can also change it up a bit by putting some Extra sits in, like walking 10 feet sit and then the next time walking 20 feet before you make him sit again. makes him keep thinking and in that aspect he has to keep paying attention to you because he doesn't know when the next command is going to come.
Personally I use pinch collars on my dogs, even though Many people Prefer the Regular Buckle collar to them. as with any collar you need to have a profesional help you Learn how to use it right, same goes for harnesses. Having a Dog with a neck injury I know how Difficult it is to train with a harness. My Min Pin has a neck injury so harness walking is the only option and I know theres a Big Size differance, but I wanted to get out there your not alone.
There is a Tips and Training Chat Tuesday nights at 10 pm est in the dog den here on Pethobbyist. You can always Come in and get some Great advice we are always willing to help!!
Sara