Previous Jap toy to my Z33 was an S15 Spec R (obviously not an S14, but near). So your petrol usage, will be a bit higher, being a heavier car. Basing on stock items, tyres are wider, so will be bit more expensive to replace. Not being a turbo, doesn't need to be serviced as often for general road driving. Parts, apply Nissan pricing, although we have some really good traders on here, that you can purchase most things you may need from.
This topic has been well discussed on here, well running costs in general, so have a nose around the forum, lots of helpful info.