Personally I would suggest you get a new report done. If the depreciation report was included in the contract (very unlikely) then you have to use it. You can use the original opening values and get the accountant to "recalibrate" it (eg things that were say $300 and completely written off may be "recalibrated to $250 and completely written off again). However, if the ATO comes knocking, how are you going to justify where you get the opening values from? If you show them the previous report they would likely say you need to use that report (without the "recalibrating") and use year 4 onwards of their depreciation schedule, thus missing out of a large chunk of depreciation. All the $300 items you can't claim and the items <$1000 would be almost completely written off.
I would bight the bullet and get a report done. You would likely be getting more deductions than getting an accountant to adjust it. Particularly if the report was one of these ones prepared by the original builder/developer as they often aren't that great.
Possibly go back to the QS who originally did it (assuming it was done by a reputable QS) and tell them you have bought the property and see if they can update it based on your purchase. Should be much cheaper than getting one done from scratch.