I just did this on Liz's 68.
You have to pull the brake shoes apart enough to get needle nose pliers in there and grab the end of the springs that go between the top and bottom of the two shoes. Then disconnect the springs from the brake shoes and remove the star wheel adjuster from the bottom. Note the direction that they were installed on each side.
Next you need to use a screwdriver compress the cup on the spring that holds each shoe to the dust cover. Once you have that compressed you need to grab the pin with your needle nose pliers and turn it 1/4 turn to release it. Then remove the shoes.
There are some decent tutorials available online.
Here is one that I used:
Corvette Parking Brake Rebuild | CorvetteMagazine.com
Good luck
