I'm assuming that "safe chat" means the plugin that the server already has, that removes the chat signing and reporting that Minecraft added in 1.19 (i think it was 1.19.1?)
The server has aspects of both already. There is a very short list of slurs that are banned (you can guess the ones). That's handled by GriefPrevention I think. I might have disabled its chat moderation though so I'm not 100% sure, either way it's definitely not the kind of language anyone on the server uses, so it's been totally fine. The "swear" level is higher than what's allowed on TPT itself, but swearing isn't common, and all slurs / offensive language are banned.
The chat signing plugin I actually removed, because it isn't necessary right now. The bungeecord proxy sits in front of the server and it doesn't support chat signing. If you use /me to write a message in 3rd person, the chat signing does make it through to other users, but I don't think it's reportable because it knows all the surrounding messages are missing. I'll consider adding the anti-chat signing plugin back when I switch to a different proxy (I think the one I have in mind supports it).