I am not too sure on reliability as have heard good and bad things about them but Japlink motors in along haberfield rd, might be worth a look in there.
I personally wouldn't touch the car you are looking at is just sounds like you are going to end spending huge amounts on someone else's problems.
I can tell you from my experience got the car looked over by the nrma and now well actually started like 1 month after i bought the car electrical issues have been coming and going... the car is being looked at once again today and the guy reckons its the alternator and that most likely won't be covered by warranty dealer or extended and this car was in perfect mechanical condition, so will see what the dealer says but thats just agood example of how a perfect car can have issues not picked up by the nrma or even a skyline mech. as these things just happen.
With the car having "moderate" issues already I would think they would just get worst, anyway probably not too helpfull but that is my experience.