Update 5/11/13 - It lives! It lives! I can get a row of Victorian bound volumes on the lower shelf of the cut-down unit, and stack say 2-3 volumes on top, and they'll be much more accessible than they were.
The "stacking two sets of shelves idea" didn't work - the units have different and incompatible tongue and groove arrangements for that - but there's room to set them up separately and clear off yet another set of shelves (this one made of steel held together with bolts) which will be OK for my sister's greenhouse or something.
