Swapping default character for custom in Sequencer

Okay, I’m aware that this question is a bit of a cheat, but I recently got someone to create a special character for me to use in one of my short films, but I don’t want to wait five weeks for them to finish so I can import the char and start animating the scene and the movements.

So I was wondering if I could just use a default char, graft all the movements onto him, record all the scenes shots and then just replace the default char with the custom one where it has all the animations and stuff rigged to them…naturally accounting for height and size different of characters.

Is there a way to do this and how without messing up all the stuff I set up for the default char? Would save a lot of time.