I am almost ready to send my 68 RS/SS off to be sandblasted except I am having a very hard time getting the wiper arms off so I can remove the cowl. Any pearls of wisdom?

There's a little metal tab with a hook connected to the underside of the wiper arm, where it fits over the wiper post.The hook snaps into an annular groove on the post. There's a tool for removing it, or you can use an offset screwdriver to lift up on the tab. When it clears the groove, the wiper arm will pop right off.