Congratulations and hats off to you. Chained dogs are often persistent jumpers on people because that's how they were able to show their excitement when somebody showed up; leaning in their collar and being told whatever they said to him, which has worked as a reinforcer, negative or not. Please do not pity him; his misery ended the moment you unchained him (yeahhhh!!!!). He needs structure, consistency and gentle training in order to belong. Observe him closely with children since you don't know him yet and he is still "honeymooning".
Also take it easy with exercise as he will be out of shape most likely. Gradually build it up.
Have a beautiful future together and keep us posted.This is so rewarding.
Deja, GSD, sable WL, female, born 11 / 2013
Cam, Rough Collie, sable, male, born 8/2015