Although DA and Rebec have given fantastic advice ,another option to try is a halti .
With most of the strong dogs we've had I've always popped a halti on as well as the check chain. I do my training with the check chain but if things get a bit out of hand or over the top then I gather up the lead of the halti , once dog has settled and placed his attention back on me then I go back to using the check chain.
With your boy being so very strong I feel ( my opinion only) that a halti would be a great tool to try with him. And Obedience training does not cost that much and is an excellent activity for both yourself and the lad .
And now just have to add that OMG! the cuteness almost stopped me from posting at all , I was happy to just keep looking