I would be very surprised if this would work. The outside front part of the seats are rounded out. The inside of the seats are straight and follow the straight line of the transmission hump.
I suggest that you pull the drivers seat out. Remove the backrest (basically 2 large allen bolts). With the bottom seat and backrest separated, flip the bottom seat over, remove the "hog clips", pull the seat cover off and restuff. You can go to any fabric store and buy the seat stuffing material.
Now, if your springs are worn out, I cant help you here.... :oops:
Another option is to remove your seat and simply take it to an auto upholstery place and have them fix it the right way. If your seat "skin" (vinyl, leather) is in good shape and all they need to do is re-stuff, my guess is it would cost less than $100 to fix.
Good Luck,
Bob
bpossel (Memphis, TN.)
'71 280SL / '97 E320