[Exhibitman]

Go for it. The item is already showing acid burns and probably has even more damage under the mat. A cleaning, de-acidification and linen mounting will make it look much better and add lifespan to it as well. I'd personally not retouch it, but I like the character some wear brings to a piece like that. Last time I did something like that was several years ago and it ran me $250 for the cleaning/de-acidification/linen mounting.

Of course, you'll have to reframe with conservation quality materials, which will add to the cost.