Well, on the upside, the various models of the genuine article tended to get modifications throughout their lives to the extent that it’s a bugger telling them apart anyway. Plenty of T-54s upgraded with T-55 mods. Your dome ventilators and radiation shielding remain the best guide to what the original article was.
Just make sure you do a spare barrel. One with bore evacuator and one without, because everyone will want the iconic 843.