Even when the sheriff has the information purged the arrest continues to be reflected on your record at the DOJ. For a conviction this old where no records exist it may be possible to get a petition for factual innocence granted. The DA can't oppose it without records. There is also the possibility of having this changed to a detention, not an arrest, pursuant to PC 851.6 which is easier to get. Your records will be changed to reflect a detention not an arrest if you win this.
As has been said, you should have an attorney look into whether a finding of factual innocence or a change from arrest to detention makes the most sense. The other advice given here covers your options.
This is general legal advice and does not apply to the facts of any particular situation or case. This advice does not constitute any type of attorney-client relationship and creates no privilege between the parties.