Swap motherboard to increase storage?

Readers Digest version: I need to replace my screen, but due to intense cracking in the glass I've lost some components to the front facing camera and ear piece. I'm looking into purchasing a 'as-is/for parts' phone to replace what is lost.

What I'd like to know is, while I'm in there, can I swap out the motherboard of an 8gb iPhone 4S for, let's say a 32gb 4S to increase my storage capability??

I'm hesitant to just try and find out, because I'm leery of damaging a perfectly good phone... Please, please, please help!