Chris,
What exactly did you grind? The inboard of the pin where the lock-nut goes??? If you havent unscrewed the pin at least 1/2 of an inch, you need to do that first before you beat on it any more.
I'd start with a breaker bar and a pipe to break the pin/bolt loose. If you need to apply heat, heat the inboard leg of the spring mount...That's where the threaded portion is.
