LTK
I have a 71 and I think it is the same as yours. My parking brake handle is atached to a rod that passes through the dash. This rod is then atached to another rod behind the dash with a quick release clip. If you get under the dash and follow the rod you will see this clip, rotate the clip off the second rod and then lift the first rod up out of the clip. This will free up the parking brake handle from the brake release. If you want to you can then completely remove the rod and handle from the dash or you can just let it hang. Good luck.
PS. I just recently removed and reinstalled a sweep dash, if you have any other questions I may be able to help.