I made this change to my side windows! its not so hard to do if you have some talent. But need to change out the window motor to a modern one so it fits between the glass and door panel! If you have a glass factory to make only 2 glasses they are very expensive , They have to make one mold for each side.
I have the molds for glasses and have 2 right side and 2 left side glasses in stock i have sold several here around Europe, They are E-marked and streetlegal made of hardened green tinted glass by a big factory that make glass for auto industry.