Just a suggestion: When you see him "misbehaving" by chewing on 'less than ideal' items, offer him one of his toys and use the word "trade". In other words, 'chew on this instead', and when he accepts the toy - praise him. And when you see him get the toy on his own, praise him again. It could help him understand that certain toys are just for those times when you want to "rip someone's head off*".
(*not meant literally, only in doggy world play)
