Ian, 
Sounds like a heart-breaker.  I wouldn't advise buying that car, unless you
wanted to put it back together as a hard-top.  In addition to the top
conversion, you would need to add support rails under the car and change the
doors.  Convertibles had steel U-channels added under the heater channels to
make up for the lost bracing that the roof provided as well as an additional
locator pin at the rear of the door.  Adding these will set you back more
than the cost of a decent convertible.

                           H Steven Dolan
                           Alexandria, VA

'73 FI'ed Westy