10 Bolt v. 12 Bolt

[ChadBice]

I'm sure this topic has been covered a million times, but my poor searching techniques haven't been able to find an answer to my question.

I have a 1971, C10 with leaf springs and a 10 bolt rear end. The engine is a 350, slightly warmed. It currently has a TH400, but I'm debating changing it to a 700R4. With that in mind, is there any reason (aside from the fact that a 12 bolt is much more durable) that I should change the rear end if the one I have is good? Some people have said that the 10 bolt is too weak for my motor. Can that be true? That's what came from the factory. If I do change it, what can be used as a donor? Thanks!