How hard to repair idler arm frame bracket

If it's rusted, there's a good chance it's rusted more than you can see. I have a 69 I'm restoring, I saw a little rust on the frame rails. Now that I've gotten everything out of the way I have found I need both frame rails, torque boxes and both shock towers.
I'm not trying to scare you, but just remember rust usually comes from the inside. So just check it out real well. You might be lucky and you could patch it with some heavy gauge metal. You can get a whole frame rail from CJ Pony Parts for less than $130.
Good Luck.
 
IIRC the idler on the 67 goes on the fender apron not the frame rails. The apron is less an invasive surgery as far a the structure goes, but still a PITA.

But as the other poster mentioned, check for other rust. If it's rusting bad there, where you can keep it somewhat clean, what do the floors look like?