Bob,

Rather then a wrecker check with the local construction contractors. A larger backhoe would work better then the wrecker. Besides the up and down movement it will also have side to side movement.

I would assemble the whole thing on the ground and hang it all at one time. Just be sure you have the split rings facing in the right direction (cone side up) when you place the head on the mast.

Our Jesus nuts were left handed because the main rotor turned counter clockwise. I don't know about cobras. Never worked on one. Good luck!