Yes, Cres is right about the documentation. 
However, these are one of a kind pieces of 
artwork that are fairly delicate to clean and 
handle. You can document everything about it, but 
I doubt you would be able to find a replacement 
(or fix it to it's original beauty), if something 
were to happen. 

If it was *me*.. with THOSE gally cels? I 
wouldn't do it. But that is just MY opinion. 
Gunnm cels are just so rare. 

Something to consider? (it's silly but...) Maybe 
have some high quality prints made of them for 
display? :D (i know it takes away from the idea 
of cels.. but......)

oh well. :D good luck.