How wet is as far as the floor pan? Was it a complete under water car or was it a severe rained wet car?
I had a top-closing problem about a half-year ago with my 300SL and this turned out to be a hydraulic "pod" that only cost US$40 (with additional repair costs/mechanic hours US$450).
The top of the R129 SL is complex enough to let the dealer take care of any hydraulic opening/closing problem...
with a minor 600+k