You should, or may all ready, be aware that there are two ways to achieve close focus/high magnification using a reversed lens. One is a single lens solution that requires an adapter from the camera body mount to the lens filter thread and the other adds a reversed lens to a normally mounted lens using an adapter to couple the two filter threads.
In your current "lenseless" state then I'd advise that you simply pick up a cheap kit lens (18-55 or 38-76) and some extension tubes with electrical contacts so that you can control the aperture.
Bob