Was looking for such a project since Zerocoin seems to be off work or at least I don't see any news on it .
Basically your project will be a .exe GUI ?? or a website ? It would be nice if you can work with some wallet to implent this feature off-chain transactions on one the wallets directly (if It's possible of course , don't have a lot of programming knowledge )
there will be a designated wallet and front end.
and i like your idea of a local application for talking to the factom network, this is possible though I am not sure if this is planned for development.