You could try growing a pot or two of 'cat grass' for him to chew.
To redirect this behaviour, away from potentially harmful things, to something 'safe'.....it cost a lot of money to have 'foreign bodies' removed from their innards!
You can also get puzzle feeders for cats. I use three different sizes including a dog's sized one! You put the cat's biscuit ration or teats inside & he has to push the ball around so that the food is dispensed slowly & randomly. This takes ages & keeps him occupied, using up a lot of his energy. It copies the natural hunting behaviour of a cat lots of 'hunting' for just a little food.
Finally, you could get a beef bone for him, to spend time licking & chewing. I say beef because it shouldn't splinter or chip.