I hope you realize that a 64-bit Wine is not going to let you run Win32 binaries, so it will only solve your problem if you have either a Win64 version of your app, or a Winelib app. But as long as you are aware of that, by all means go ahead, I don't think anybody else is working on that at the moment.
Alexandre,
Thanks for your perspective. Is this largely because WINE is not an emulator? I would have thought it possible to have WINE itself compiled as a 64 bit application (such that it can pick up and use 64 bit linux libraries), but still represent itself as a 32 bit environment for the windows binaries. But, you know way more about it than I do - if you say that isn't possible, then I won't bother starting.
Sean.