Beautiful ivory Ma'am.
I too was skeptical about your original post. Glad I'm wrong.
When you say they are one of the eight largest sets in the world, I presume this is based on SCI from looking at the photos, not Rowland Ward. Your ivory would not be in the top eight in the Rowland Ward book. I don't mean this as an insult because your ivory is truly amazing. Especially for this day and age.
Not sure if you are interested but there is some large ivory in the following thread. Please post a photo of your ivory. It certainly belongs there.
http://www.africahunting.com/thread...-magnificent-seven-big-tusker-elephants.3415/
Just some thoughts on possible buyers:
I agree with PHOENIX PHIL. He is wise in saying not to give out too much information on a public forum. I would love to know the weights of your tusks, but people might be able to figure out who you are if they check out the record books and your ivory is recorded there. If not, please share the weights. If I read the new July 2016 regulations correct and there is no longer any interstate commerce in ivory, Cabelas may be one of your best bets as far as selling them. You might also check with other sporting goods like Bass Pro, Gander Mountain, etc. If they have a business in your state, they should be able to buy them. Then as their property, move them to another location if they want. I am not an attorney and don't know this for sure.
Lollibros (an auction house)
http://lollibros.com/ used to sell ivory and they may still. They should know the rules. I was at a sale there about 10 years ago and pre 75 ivory was selling for about $120-150 per pound, depending on the size and quality. None of the tusks were over apx. 60lbs.
There used to be an ivory buyer that advertised in the back of Safari Club Magazine. His name started with a Z. (don't remember it) Not sure if he still does this. He would buy pre75 ivory and cut it up and sell to craftsmen. I no longer am a member of SCI so I don't receive their magazine. Possibly some one could check and see if he is still doing this. 15-20 years ago he was buying around $100lb if I remember correct. He was advertising as recently as three years ago as I remember.
With ivory of the size you are talking about, you might try Christies or Sotheby's. Your tusks certainly would qualify as collectors items. They would have people that know the legalities of what you are trying to do.
A couple of years ago I read that black market ivory in the far east was going around $800-1,000 lb. Not sure if this is correct and this of course is illegal but thought I would share it with you to show what the government has done. You have legal private property and in essence, the federal government is denying you the right to sell it. Sure seems like the "taking clause" , but what do I know.
About 15 years ago I was contacted by an insurance appraiser. He wanted to know the value of ivory. A friend had referred him to me. I told him I was no expert, but would be happy to help. He told me he was trying to get a value on a set of ivory. He said the total weight was 360lbs. I told him he was wrong. He swore he was right and he had weighed the ivory himself. (There was some filler stuffed into the nerve endings that wasn't removed to weigh the ivory) He gave me more information that made me believe him.
I wasn't able to help him much, but pointed him in some other directions to establish value. I asked him to get back with me once he was done to let me know what he found out. He called me a few weeks later and said they had insured the ivory for $1,000lb or $360,000. He said in his research, with this ivory probably being one of the four largest in private hands, they were probably worth apx. $10,000,000 to a collector in the middle east. Unfortunately getting it there is illegal from what I understand.
If you have any questions you don't feel comfortable sharing on a public forum, feel free to pm me. Not sure I can help any more than I already have though.
All the best in your endeavors and thanks again for sharing a truly beautiful set of ivory!
Here's a photo: 
