What a non body professional would see as "no rust throughs" and "very minimal" as for rust, that honestly means nothing. Believe me, after being in this business for years you can spot where rust WAS or hidden where there is NO SIGN what so ever of the rust, but just buy how it looks you can tell what has been done. So having a pro look at a car like this is very important.
I have looked at many cars for people over the years, it has always been a free service of mine when I had my shop and where I am working now, we will put it up on the lift and check it out well, all for no fee because we feel it is so important to our customers.
I have seen some that were friggin wild! I had one that the car was spliced made from two cars, done VERY poorly. The car had very low miles and the motor and interior looked like a brand new car. As I told the customer, "It has low miles because it has spent the majority of it's life in a salvage yard!" I told them to go back to the wholesaler who is trying to sell it to them and THROW the keys at them!
Another that comes to mind was a 70 Camaro (this was back around 1982) that one of my customers was buying for his 16 year old daughters first car. The car was lowered and it had it's front fender wells torched out to clear the tires! One hard bump and the tire it's the ruff edge of the torched hole and rips the tires to shreds! At highway speeds we are talking possible flipping of the car and death! Again, he brought the car back and his daughter got a little more conservative car.