Don't understand what ????? If he touched one of the wires to a ground (dash) it would have sparked and possibly blown the fuse link. What were you thinking happened?
If you read my post carefully you would know what I m trying to help him with. If you replace the fusible link and something is touching the red ammeter wire ( remember he replaced his ignition switch), something may have moved behind the dash and the link will blow again or worse wont blow and instead the red ammeter wire will fry and potentially start a fire. If you re simply replacing an ignition switch why would that cause a spark behind the dash when you turn the key? Possible answers are faulty ignition switch, or something with power is touching ground, hence the blown fusible link. In my 30 plus years of working on everything from Desotos to Imperials to Miradas but mainly early a bodies I have seen many fusible links not blow and the red ammeter wire fry instead. I am only trying to help this guy through my experience dealing with similar issues, which I though this forum is all about. Maybe I am wrong, I just started to contribute to posts.