Heya Maxie and welcome!
I am not an authority on these cars, but I want to give you some things to think about. Hopefully it will help you to find the right car for your wife.
First and foremost, Spoolfool said it best, if she is craving a GN, we need to know if she has sisters, or would be open-minded to cloning. (haha)
Okay, seriously now. The first thing you are going to need is someone to work on the car. I get the impression since she has driven modified cars in the past, that you guys have a resource for that. (Be it you, her, or someone you know). In addition to having someone who can turn the wrench, it is important to link up with the Turbo guys in your area. These cars, when not sorted out, can drive even the most experienced mechanics crazy. Getting in with the local guys, who know all the nuances of these cars will save you lots of time and money. They are 30 years old. The good news is that most everything that fails on the cars, the knowledgeable folks here know about. Imagine replacing your cars Alternator, Battery, Battery cables and re-located the grounds (all on your dime) because your car wasn't charging correctly. Now imagine a knowledgeable person would have told you to check the lightbulb socket on the volts light since a GN wont charge properly if that isn't seated correctly and making a good connection and the dashboard shifts over time and the dried out wires could lose their contact. It's the kind of thing that will drive you nuts, and your average mechanic doesn't deal with every day.
Before I comment about the car you posted about, I think it is important you identify the list of qualities you want the GN to posses. From what I gathered so far, reliability is your top requirement. If that is true, remember that with high performance, generally comes higher maintenance and reliability can be compromised if you are not 100% familiar with what is done to the car. Generally speaking, the 'safest' advice for a truly reliable car is to get one as close to stock as possible, one that was well cared for, and you do all the mods yourself. That way you aren't chasing down someone else's gremlins. Generally speaking I advise avoiding cars that have had major engine work less than 2 years priors to being listed for sale or cars that have been heavily modified that haven't seen the street for at least two years in a row. A reliable GN is one that has been running without issue consistently. You don't want a car that someone was able to 'get running again' and looking to sell off. (There are of course exceptions to everything)
Okay so in regards to the car you posted, it clearly has been designed to be raced at the track. Ya generally don't have a trans brake installed unless you are taking your launches and track time slips seriously. What that tells me is that this particular car was built to be raced, by a racer. This isn't inherently bad, but it places greater emphasis on knowing EXACTLY what was done to the motor, when, and by whom. One of the posters above identified some performance parts that are 'dated'. This also isn't bad, BUT if the car was being raced this whole time, those parts could be well worn and potentially be due for service. The flipside is that if your mods were done last summer, it would seem odd that the car is listed for sale so quickly.
You mentioned you have a few in your area for sale. Here is my advice. Pretend money is no object. Search the entire country for GNs. See what is out there, how the ads look, what mods are listed, and what the prices are. (Again pretend money is no object). Get an idea of what you 'could' have. Reading all the ads will make you feel better or worse about the cars in your area. Don't railroad yourself into buying the first GN you see, or picking from the litter that is close to you. Also buy as much car as you can afford. These cars will nickle and dime you (only the nickles seem to only come in $500 increments haha). Many GN fans have had their dream ruined by purchasing another guys mistakes.
A stock GN, properly tuned is an animal. Lightly modded with some bolt on parts and they are a beast. A full blown race engine and trans, built by a performance shop sounds like a monster. I am not certain the first GN in your stable should be a monster. Monsters tend to be kept in their cage (garage) more than they are roaming free. My gut tells me this may not be the GN for your wife, but as I disclaimed I am not an authority on these cars.
Good Luck in your search, an let us know what you decide!