At $750 here's your tally
1- You can't look at acid damage because you don't have the keys to the backbox. I would go to home depot get teh right screw driver $10-$15 bucks and unscrew the lock. Check for burn molex connectors, and acid damage even before committing to this.
2. If you get this you'll have to pay $200 for a new DMD unless it's just cracked pins that are preventing the display to perform properly.
3. A lot of playfield cleaning and at this point probably a new playfield in the future but since you'll have to take the machine apart to clean in all I suggest you try to find a T2 playfield. $750 ish. You could also get an artist to repaint the wood areas as they are mostly black and then get the playfield clearcoated.
4. probably will have to change some switches, lights etc...
5. The corner cab would have to be glued with epoxy.
At $750 it's somewhat high because of all the work you will have to go into this. If you wish to learn and don't mind spending $750.... You can find T2 deals once in a while $1500-$2500 range and you won't have to break your balls or your wallet to enjoy the pin. But if you decide to buy...it will be a real learning experience.
Check #1 before committing. Boards will kills this deal if they are damaged. And since he doesn't have the keys. Who knows when the batteries were last changed.
As is $600-650.