I did the same thing to my 87 about a year ago
with the car up on ramps you can access the starter pretty easily..
take off the heat shield attached to the starter, then there are 3 bolts holding the starter in place
If you can find the cabriolet forum on this site, there is a great pictorial write up about fixing a toque convertor seal... there are awesome helpful photos of removing the starter.
Get is raised up enough to work under and the task is not very difficult