If you want a skyline then a non turbo would be fine, ive driven both turbo and non turbo 33's and both a good cars. Obviously non turbo's are alot tamer but are still are a solid car.
If its everything that you want then it will be worth it, but u will want a turbo fairly quickly (dont bother putting one on, just buy a new one).
Some police know jack shit, most know more than we would like. Just dont get a atmo bov and if you get a pod then cover it up somehow and you should be fine.
I would just look on carsales or the for sale forum here.
Anything else you should know? Well this forum taught me ALOT of stuff about them so start there.