Sorry, a little slow to respond here.
I think James has summarised the situation well although I believe my circumstances are somewhat different.
I am moored on a buoy in a fairly sheltered part of Poole harbour. It does not dry out, as such, but on a spring tide it can get rather shallow. As a result, I always leave the keel about halfway. The leading eyebolt has the pulley mechanism, the other I has a 5mm dynema rope on an elastic cord; the former I have looped so that I can raise the keel halfway and support with a 'bolt', protected by a piece of wood. Sounds a bit Heath Robinson but works well. When I sail, I remove the bolt and, depending on the wind, sail like that dropping the keel, if necessary, when the wind picks up. Also helps - being lazy – if I don’t need to lower/raise the keel so much.
I was not really ware about the issues of the keel movement when the boat is 'inverted' so can’t really comment. When I have lifted the keel right up out of the housing (twice) so that I could replace the eyebolts, I had to remove part of the side mechanism. But being an older boat, perhaps that is why!
Raising the engine right out of the water, I have a wooden contraption which the engine sits on. At the moment, fortunately I don’t have a problem lifting the engine. – at least no more than raising the keel. I get right over the engine and lift accordingly.
I hope to go to the boat tomorrow so will takes some pics and try to most them here.
Talk soon