Ralph, I have seen boys hold those headers up with chains around the header support pipe. You know, the round pipe that angles back at the top rear of the header. I never thought those were strong enough but haven't ever seen wear to suggest they aren't. If it were me I would sling strap around the feeder house at the base and then around the header, lift at that point having someone steady it with ropes tied to the ends. To unhook it I would do it without lifting it as that will jack with the geometry making pulling those pins harder.
If I remember right those pins are about 8 inches long and shaped like an "L". The top of them is not like a pin used for pulling implements. More like something little boys would use to play cowboys and Indians. Sorry, First Nation's People.
While you have that header off check the condition of the sprocket bearing that is right there. That's the one we would have to remove the header to replace. Booger.