If the upper metal is that badly rusted, it makes one wonder if there is anything left on the bottom side.
You're probably right, there is probably rust in every nook & cranny.
Now that I think about it, being from NYC it may have even been a victim of Hurricane Sandy.
If I had more time, space & no other projects, I would consider the 2 hour drive to look at it but I can't. I had a 1971 Barracuda a few years back & sold it because I was overwhelmed. If this car wasn't in NYC I would take a chance & go see it, but the tolls & gas to get there with a trailer would probably be more than this roach is worth.