IMHO thee key factor that causes a tipping point as to whether, or not, to keep such a car is the amount of rust.
Mechanical/electrical problems, for example, may be overcome, however, the amount of rust may reach a point where it becomes time to cut bait, and start over.
I realize that money is a factor, yet I will write that if I indeed had a 97 Sport with no rust, or very little rust, I would make an effort to invest in making the car at least a sound car, if not a bonafide attention getter.
1995 Thunderbird LX 4.6l 97 Headlamps/Hood All Red Tails Muffler/Resonator Delete
2004 Tahoe 5.3 4x4
2008 Acadia Limited AWD
...still looking for a clean, low mileage, rust free 96/97 Thunderbird 4.6