Jim,
At the last Tech Session in 2003, Cees Klumper taught me a trick: when the top is folded to be stored in its spot, you need to, by hand, fold the corners under themselves. I did this and when the top comes back up, the corners don't get all bent and mangled.
Pete Lesler also tells me that you can get a new clear rear plastic window. I assume if this is available, you could find an upholstery shop to stitch it in place and replace that rear window of yours.
Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored