I had this done as a temporary measure on the 280 - I knew I would repaint the car and replace the top but wanted a clear window while doing a rolling restoration. It served it's purpose.
The shop that did it, removed the top from the frame and replaced the clear plastic and reinstalled the top - I think I was charged about us$300.
Two issues to note: since they removed the top from frame, you can see previous glue in area on the fabric and on the frame. Also, for whatever reason, they did not sandwich the new clear material between the soft top fabric as originally done - they overlapped it on the inside. You can only see it if you were looking for it. I let it all go and did not complain since this was a temporary fix for me - it bothered me, but not worth it since it was temp.
I now have a new top to install once I finish the new interior.
So it is doable, but be clear (pun intended) if your old top is worth saving and be clear how they will stitch new clear plastic in addition to seeing some glue marks.