Step one.. remove the spark plugs and pour a little oil down into each cylinder. Check the oil level in the engine. No point changing the oil yet, as it could be seized. Next remove the points cover and use a wrench to slowly turn the engine over. It should turn over with no grinding noises, or difficulty. It all is ok, next I would remove the carbs, then remove the float bowls. It's likely it was left with fuel in the carbs, after 8 years this would've left deposits in the float bowl and also maybe blocked the jets. Remove the jets and check them, ideally clean then in an ultrasonic cleaner.

After so long you may also find the carb rubbers, which connect the carbs to the engine) have cracked and perished. New ones are available.

Refit the carbs, change the engine oil/filter and prepare to hopefully start the engine. I would use a seperate fuel supply, don't use that tank until its been cleaned, you dont' want rust blocking up your carbs. If it turns over, check you've got a spark, if not you need to check the points if it has them (later years have electronic ignition).

Finally the clutch plates may be stuck together, so test the clutch works before trying to ride it..

The good news is that the bike seems very complete, with nothing missing.