It's hard to know from pics, but I see areas of concern. If the price is really good, I'd dig into it further. You need to go all around the frame, especially in the known weak areas, and bang on it a bit. I use a pointed chipping hammer. You don't have to swing it too hard, and you will feel immediately if you hit a soft area as its like hitting foam instead of steel, and the hammer will likely sink thru the frame. Ask the owner before you do this of course. If the hammer goes thru the frame, you didn't make anything worse, it was already no good. Stick your finger in all the holes and feel around. If it feels rough and rusty, that's an issue. If it's full of shit (many are) that's an issue. Poke between the skid plate and frame with a screwdriver, if it goes thru, try to see if it's going into the frame or just between skid and frame (some years have a small gap). As the other poster said, a endoscope can really help. Check all the floor pans and torque boxes as well. These are thinner metal, you don't need to bang on them, it will be pretty obvious if they are rusted thru. Pull up the carpet and look from underneath. Look at the tops of the front fenders, rocker panels, etc. With this much scale, you will run into rusted bolts, breaking bolts, definitely rear upper shock bolt issues, etc so be warned.
If you take your time and do all of this right, and it looks good, it *might* be worth purchasing, but I'd want it cheap due to the scaling. Read that as around $4k, preferably less. This is assuming it runs and drives well with no obvious mechanical issues.