Imo the only post that made sense was the last one. I'd not use any modern turkey load. The gun is a classic why punish it/test it.
Turkey guns can be had relatively cheaply if you wanted to really get the "most from your hunts" in a sense. On the other hand you may get more w the old gun especially if it has sentimental value.
Me though if that was the case I'd still not use it every day, dragging it in the rain, scuffing it on rocks, etc n in general pounding it and I'd certainly be easy on it shell wise.