The two plates for the lower ball joint separate fairly easliy once the rivets are out. I would not recommend re-using the gasket, but keep it as a template for making new ones. Also, when you re-assemble the ball joint, you will need to clamp/press the two plates together and then hammer the plate tabs to get a tight seal.
After I tumble the LCAs (sans ball joint), I use gun bluing and a torch to get the heat treated appearance of the plate that is spot welded to the LCA.
Regards,
Pete Morgan