I read that Jack Bodenmann build such a lubricator for a locomotive he's working on. Might contact him, as he's very helpful to others. www.jbodenmann.com
Would it not be possible to just substitute a miniature sprag clutch in place of the ratchet? You might have to experiment with the angular movement to get the clutch to grip which may be more or less than the ratchet method.
the ratchet does have that old- time thing going for it . I had some trouble with the out put valve on the one I built . the design that works best for me used an o ring for sealing