I really like your crane.
After seeing you engine crane it reminded me of an adventure a buddy and I had with a boat motor. He needed to put the motor back in after a rebuild but did not have anything to use. We came up with a moveable crane by using his van with 2 pipes in a “V” shape mounted to the front bumper. And a chain leading from the top of the “V’ over the van to the back bumper. We put wood at the top corner of the van so the chain did not dent the van roof. And we put a chain fall from the top of the “V” to lift the motor. It worked great we picked up the motor and drove the van to the boat and lowered the motor in. Had to make a few up and down movements to get it in final position. All went very well. We did not have a single long chain for over the van so we used easy links to connect sections together. Well after the move was done and we started to take it all apart we found one of the easy links was not connected. And it had stretched out and the only thing holding the chain together was the bump made by the threaded part of the link. Here is a picture of that link. This is one day where luck won over skill.

Have fun
tom