honestly if he doesn't like puppies it might not be a good idea to bring home puppies. He's 8 that is on the upper end of a german shepherds life span, if you know you are going to stress him out more why get puppies he hasn't met and likes?
Probably good introduction between them is very essential. They should be familiarized with each first like through scent so they will be aware they will new ones. I always watching Cesar Milan tv show and seen lots of dog cases like yours so it may help if you watch Dog Whisperer too.