Looks like you let Michael J. Fox take the photo with his camera phone!
Good choice with a mtb rear wheel. The width will make it a bit more stable at slow speeds. Did you try taking a hammer to the seized stems? You should try to do it properly, otherwise how will you get a headset on the top frame? If you have no headset the conduit just rattles in the head tube and makes for a very unnerving ride (I know from experience, haha).