Something has definitely come in contact with the piston, but I would not change it.
To be fair, I would not even replace the head gasket on a 3.8 in a t-bird. That car can house a 5.0, 4.6 sohc, or even a 4.6 dohc. Even if he cares nothing about performance, any of the other options would increase the enjoyment of daily driving and increase the reliability. My limited experience with the 3.8 t-bird (had a roommate/friend with one), was that the motors are nothing but problems with no bright side. Little power and poor fuel economy.
I would do one of two things...1. put it back together as cheaply as possible and drive it or 2. get a complete donor and swap in a better drivetrain.
Edited to add that I love a project and love to see people working on their cars, but I just really don't like the 3.0/3.8 motors. Head gasket problems and other issues are common and there doesn't seem to be any redeeming upside to ownership.