Carpentry and Woodworking - Restore an antique carved window

I bought a set of Chinese carved windows. The size of each one is about 3ft wide 4 ft tall. There are some intricate carvings of patterns and very intricate sceneries and figures. One can see through the window from the pattern portion. The material for the frame seemed like pine, and the carved portion was campher as I was told. The windows are over 150 year old, and I am still cleaning the dust and dirt at this time. My question is what type of finish I should put on the windows to preserve the antique. There were no nails used during the construction of these two windows.

It seems that the first thing to do is to determine what finish is on them now. I suspect that the finish is shellac. If that be the case, it is easy to repair and restore. Much help in this matter can be gotten from sites and books more dedicated to restoring antiques than just spot recommendation such as mine.

Very surprisingly, there was no aditional finish beyond the wood surface. The windows were removed from an old house in the last year or so, and the surfaces were bare. That is why I have no direction.