I would absolutely not consider rebarreling one, although in theory this may be possible. I had a 7400 and it was the worst rifle I ever owned. Unreliable, hard-kicking, and inaccurate. Also suffered from a wandering POI. The trigger sucks, and the receiver is a pot metal piece of garbage.
I would look for an used BAR in 35 Whelen or 338 Win Mag. Still not a perfect rifle, but better than a 740/760/7400.