Doctor Herbie wrote:
Also, it's not a welded fender bolt. They were compression fit at the factory to save on welding costs. (Though the replacement can and should be welded.)

Which is why the damage isn't worse (forgive me, I called them weld nuts because that's what the replacements are called).  Dylan, I can only recommend that you find yourself a fender to use and make sure it's going to fit before going any further.  No point spending time on the car only to later learn that the body is tweaked worse than you thought.  No harm trying to fit it yourself first.  It might not be that bad (I've fitted fenders to wrecked cars before with a surprisingly small amount of trouble). 

Just keep this pointer in mind, it's important: Decide on and stick with a routine for bolting the fender up, always putting the same bolts in the same places at the same time.  For example, I start with the one at the very top/center, and then do the one to the left, then the right, then further left, then further right, etc., until they're all in.  Only put them in a few turns at first, never drive them all the way in until they're all in place.  I used to have no method to doing this, and sometimes I'd start in the middle and do all the left, then all the right, or I'd start in the middle and then do the two ends next, etc.  I'd get a fender perfectly fit, only to find that it was way off next time I put it on.  I finally realized that not having a method to mounting it is the reason for this inconsistency, and I haven't had a problem since.

Of course, you'll need to replace the torn out mounts before you start.  You could just use a regular nut and bolt, but this is the "easy" way and will also require someone else there to help you.

Dan