I have never heard of a guinea pig being harmed by cage chewing. It should be fine. However, in the larger cage, you will probably find that they don't chew as much, at least not on the cage!
One of my girls thinks she is a beaver, she chews her companions hair, (they are long hairs and apparently she thinks that is odd and they need help, being short haired herself!
) Also, she does chew on the coroplast. You can slow that down by putting binder edging along it, I have just opted to replace it in the coming months.
Try some organic Apple wood chews in the cage, toilet paper rolls (cut down the side) and of course, make sure they have unlimited grass hay! That is really important. If for any reason, my pigs run out, that when the majority of the chewing happens. It is not often, but when it does happen, Watch out!