the object 260 would be perfect for an event vehicle
i believe it was either a fully fake tank made by wargaming or it was basically the IS-7 as by just a simple google search it appears that the OBJ 260 was the project name for the IS-7 so no real new tank to add and the IS-7 is already in game and was done as an event
Object 260 was the designation for the IS-7 and its early prototypes.
The one represented in WoT is the IS-7 1946, for which a suggestion is here: IS-7 model 1946. The forgotten older brother.
It was real, although there were basically no photos publicly available up until a short while ago
The Object 260 was the predecessor of the IS7
but only on paper because IS7 was better
The GABTU index (object 260) and the army official names (IS-7, though not really) are coexistant. The GABTU index doesn’t preceed any other name, and is still used after adoption in certain curcumstances.
The vehicle is both IS-7 and object 260 at all points in its development. And as ChieftainWarrior pointed out, my suggestion contains the earliest built IS-7/object 260. The WoT variant was never built, but the 1946 model is very close in both looks and performance.
The one represented in WoT would actually be a 1945 variant, since it carries the 122mm BL-13-1, and thus was never built.
I think there’s some things to say about how accurately it’s modeled too, but that’s another discussion.