What would a pro detailler do differently though? They'd clay it out too! Just need to polish it out afterwards!
Well once he's clayed the car, it might end up getting covered in light scratches, so it would need machining, imo.
I've bought 2 Zeds with high mileage one was at 72k and the one i got now is on 83k. I had a dyno session last year and the car pulled as strong as an 06 roadster with less than 30k, in fact it beat it hands down on bhp and tourqe outputs. The engines are pretty much bullet proof if regulary maintained and not ragged. So the answer to your question is, how long is a piece of string
If your car has only done 9k i wouldn't worry about gearbox oil and spark plugs, that's a long way off. All 350z's have lsd's and no maintenance required. Saying that its good practice to change the box and diff oils at about 50k but not necessary