You've already taken the first step by posting a reply on the original thread. The original requester said "Feel free to comment on the photos or right here," so you can either leave a comment on the Google Photo page for each headstone, or you can leave your transcriptions in the original G2G thread.
Or, if you don't get a response in that thread (it's only been 10 hours even now), you can try sending a private message to Childs-1667 to get his or her attention that way.