I purchased an '86 gxl and noticed some damage while changing the oil. Under the driver side door, a little further under the car, past the pinch weld, there looks like a structure resembling what could be a frame or subframe. This structure looks like it has been used as the point to jack the car up, but now looks crushed and dented in. I love my 7, but I don't want to waste money on a car that cannot be perfectly restored. I am wondering if this can be repaired(reliably) or if anyone has any experience with this type of damage. Thanks for your time.

 

That is fairly common with these cars as people buy them and then jack them up using that "rail" and it will NOT hold the weight of the car soundly.
It will squish to put it mildly.
The Jacking points are in the Frequently asked Questions.

Now,IF the car is Pristine then I would understand you wanting to fix it back to original,BUT it will not affect the car's ability to drive.
The only way I can think of is to get it redone and that means getting a Welder to take it back out(heat and form) OR make another rail and place on the crushed rail...a Big task for a small mistake.

Oh..don't jack the car up..on that spot...(see what happens??)
Use the DIFF or the engine cross member or A arm points.