By the sounds of it 2 possibly 3 things might be stuck. Drive shaft, water feed pipe or the exhaust tube (normally the bottom of the exhaust tube can be quite stubborn)
The square drive shaft that runs down the inside of the smaller of the 2 tubes could be slightly stuck (although i am seeing a small gap in the flange) but my money is on the water feed pipe (inside the exhaust tube) being stuck in the pump-housing. Don't worry about the exhaust tube to cylinder joint for now as that will come a bit later. As your motor is a direct drive there wont be any hidden linkage, it's just stuck in place from corrosion and time.
From my (limited) experience, the water delivery/feed pipe can be a nasty little so and so to shift. Pot luck here really on which part begins to move first, either the feed pipe or the exhaust tube. I would proceed by heating the exhaust outlet on the pump-housing. The front face of the exhaust flange (in between the 2 tubes) is where the delivery pipe runs inside. Lightly tap the pump-housing downwards and if you're lucky the pipe will start to come out. If not, then more heating and tapping i'm afraid! If all else fails at this point, your only option left is to try and shift the exhaust tube downwards (off its flange on the cylinder) so as to uncover the pipe attaching nut. Undo the nut and it will hopefully come apart.
If you have a vice in that lovely workshop of yours, once separated from the lower unit carefully clamp the cylinder (not too tight now) in the vice which will help while you work on shifting the exhaust tube from the cylinder base. HEAT (we've gone over this a lot now) is your best friend don't forget. I would slacken off the pinch bolt at the exhaust clamp and slide it down the tube so it's out of the way unless you've done so already. Set to on the exhaust tube for a short while with your blow torch and at the same time gently rock the tube back and forth it should start to work itself loose. It will be a tight fit against the exhaust flange and you might even notice 4 small slash cuts to the tube.(hidden by the clamp) Try not to spread these slots too far open as when you come to re-fit the tube to the cylinder it will end up being a very loose fit.
Gently does it and try not to force things too hard.
Eventually it will come apart.
All quite normal for a motor that hasn't been apart in many a year i'm afraid.
Stick with it as the fun is just beginning.
Best of luck
Jon
