If no one chimes in you might want to check Yellow Freight. I've had Mini engines and gearboxes sent to me this way.
Seller drains the fluids, wraps the engine in plastic to keep it from any drips, then wraps in cardboard and another layer of plastic then straps it down to a pallet. Right or wrong the last chap just got the pallet from a HD back lot or similar. Got one just big enough to fit with a little extra overhang so a fork lift at the shipper could move it around.
Then got a couple of trailer tie downs and strapped the engine "parcel" to the pallet securely. Drove over to the local Yellow Freight terminal and shipped it.
Seems he ships a lot this way. Says the cardboard is to stop the engine being visible when shipped and to help soak up anything that might still be leaking so there is not some big MSDS type issue. I did notice he put the shipping item down as household goods.
Either way, the shipment did not take long and when it arrived at the local terminal I just went down there with a mate who has a truck and they loaded it in the back and Bob's your Mother's brother it was done.
I had a copy of the invoice somewhere on the computer, but can't find it. Seems like the cost was only $100-150 from California to here. There was a post asking after a transport section. Think I had the invoice then and posted exactly how much it was.
Think a transport section is a great idea. Classic Mini community has been doing it for a while and it has worked well. Of course, board has to put a disclaimer of liability on any deals done. This day and age......
Best of luck with it.
