Well, somebody might have back in the day. I thought I might have seen a pic of one floating out on the net. Closest you are going to get now is from:
http://www.usbodysource.com/ They sell a kit to convert a regular cab truck to convertible. The top looks like the front half of a 73-75 K5 top, but with the back like a truck cab. The back wall does not extend to the floor like the 1st gen kits did since it's for a truck, not a blazer. One could fab up a cargo wall to meet up with the lid though.
Looking back at the website, they only sell the top with a fiberglass truck cab. $5900 (ouch). Might be able to call them and see what the can do.
Edit---They do sell the top separately. Still it's $999. Look at the bottom of the list on the 73-87 page. It's the last item listed before the pics.