P0018/P0300 repair suggestion

Question

I know that the timing chain tensioners need to be replaced, and ultimately the timing chain itself,  but the repair guy wants to pull the valve covers to make sure everything in there is in good condition, before he proceeds with the chain replacement. He also recommended replacing the water pump as well.
It makes sense to me, but I'm curious if he's putting more into it than needs to be. It's not a cheap repair, that's for sure