I don't know that any of them really sound the same. I would have to say maybe G12-65 because it's one of the only celestions that doesn't have the cutting top end. Maybe a CL80 would have similarities as well but it has a brighter top end and more "squonky" growl if that makes sense, lol.
I think some of the warehouse speakers have a similar sound, such as the ET-65 and the V30 inspired models. I've played a VHT 412 with the P50s but never back to back with the other speakers I mentioned so I'm going off of memory.