To answer the OP's question, like i said before definitely post a topic in the V-Series Skylines section you will receive a good amount of information on the 350GT's. I also think it might be difficult for you to find one exactly as you have mentioned as a lot of these cars are Premium models.
The good: They are powerful and reasonably priced cars, 206KW at the fly stock. They are very attractive cars, attracts attention as a big population of people don't know what they are. Very modern in terms of accessories and features.
the bad: they aren't cheap to buy parts, servicing is an issue as most places don't like to touch them, insurance is through the roof, suspension bushes are shit from stock and need replacing pretty fast.
I can think of a lot more things to mention but i'm at work and can't give a fully detailed post at this point in time