I found these drawings of frame rivet tools on the g503 restoration
board.
http://www.g503.com/boards/
They were in response to a thread on using rivets.
The specific thread was at :
http://www.g503.com/boards/g503/msg-tech/3673.htm
You may be able to find them at http://jeepdraw.maryboroughqld.com/ by now with more details.
Drawings were by a Paolo Batisti from what I gathered in the message link above..