1. Styrofoam peanuts for heavy items are SHIT....
2. PLEASE assume that anyone other than yourself will do an insufficient packing job, they just don`t understand that your item must be treated like a rare historical artifact that cannot be replaced.
3. Two boxes will be needed, the item being suspended and centered within the inner box. Something with a bit of "give" to it, like the high-density polyurethane foam that glass displays, mirrors, etc. come packed in should be used to protect glass panels, switches, and corners. There should be NO movement within this inner box when shaken.
4. The inner box should go into an outer box that is at least 2 to three inches larger than the inner box. Safety factor can be increased by cutting the corners out of several other boxes, and using construction adhesive (Liquid Nails, Gorilla Glue, etc.) to fasten those cut corners into the outer box, overlapping them 2 or 3 layers deep will greatly increase corner strength.
5. More poly foam is the ideal cushioning material for between the two boxes, if you don`t have enough, go to Plan B....believe it or not, 3 full sheets of newspaper, wadded up TIGHTLY like the size of a baseball, and stuffed between the two boxes, works quite well as long as a sufficient number of them are packed in there. Again, the aim is to prevent any movement between the inner & outer boxes.
The outer box should be sealed, then reinforced with nylon-impregnated strapping tape applied in a tic-tac-toe shaped pattern.
One caveat....to be insured, the shipping company might require that the burst strength of your boxes must exceed the weight of the package. Find this out before packing anything for shipment.
Good luck !