Why not buy new boxes from Von Schweikert? That will add to the cost, but it would be the best way to go about it. Did you mean 60# each? If so, you would be safest by securing them to a pallet. I have heard many tales of woe from members who shipped speakers only to have them destroyed in transit. Choose your freight carrier wisely. Cheapest may not be the best. I received a trashed pair of Thiel CS2.4s a month ago, so I speak from experience. They were not properly packed. I found another pair at a great price, so I spent the money to have them crated and shipped air freight. The total cost of crating and shipping was $475, but they arrived in perfect shape.
Good luck!!
Good luck!!