I really don't think that is that bad. 50 year old car that has survived going through hell and back and that's all the rust you got. It was probably like my car with rubber floor mat that was notorious for holding moisture in and rotting floors. .... pretty standard, really
The one piece repop floor pan and some ospho will take care of that or you can get the floor pan halves.
As halfafish mentioned, check everywhere. But it's not really that bad and 8 hundo is doing petty good for a classic that you can hardly buy anymore. These cars are not around every corner anymore so to have one this good is pretty special.
