Absolutely have to agree with Redhawk...if you want a barrel to shoot a certain round, by all means, go buy that barrel...that's what they're made for. For goodness sake, another barrel shouldn't break the bank.
I, personally, would not even think of trying to shoot a 460 or 454 out of a 45/410 barrel. As was mentioned before, pressures are way, way too high for Contender frames. You're asking for bigtime trouble if you do try it.
If you want to shoot a 454 or 460, buy an Encore, and the barrel of your choice, but let the 45/410 Contender barrel to the 45 and 410 rounds.