Louisiana will restore firearms rights 10 years after the completion of a sentence, assuming the offender hasn't had another felony conviction in that time. That's the good news.
Unfortunately, however, the bad news is that the Federal government also took away your Federal rights with your felony conviction. And without your Federal gun rights even after 40 years, your state gun rights are meaningless.
Louisiana, as I have indicated, will restore your gun rights after ten years and some of your rights after your sentence has been served, but they won't automatically restore ALL of your civil rights, and that is what the Federal government will require before they lift their bar against your Federal gun rights.
Your right to sit on a jury in Louisiana, for example, requires a pardon from your governor. That means to get all of your rights back and your Federal 2nd amendment rights restored, you will need a pardon from the governor of Louisiana.
Without a pardon, even though Louisiana has given you back your gun rights, you could still be arrested by the Federal government for being a felon in possession of a firearm.
Here is the Louisiana Pardon application. No lawyer is needed for a pardon, but there are lawyers who specialize in pardons, expungements and the restoration of rights, and you may want to consult with one.