And even if you're touching that part of the system, you can usually replace like-for-like without bringing it all up to current code, even if the current condition is non-compliant, you can generally put it back to the same level of non-compliance, even if it's with entirely new parts. (I'm not arguing that that's a good idea to elect as a property owner, but rather that NEC does not require "you touch it, you have to fully modernize it". This will likely invite an argument with the AHJ's inspector, if the work is subject to inspection.)