Andy
I have never taken an 1100 engine apart so I may be wrong. However I have a 900 engine in pieces in front of me.
I believe you should be able to take the crank cases apart without removing the barrels and then yes you will be able to remove the gearbox and shafts from the bottom. You should then be able to remove the big end nuts from the connecting rods which will allow you to part the big ends and thus take the crankshaft out. Obviously this will leave the pistons and con rods still in the barrels but my thinking is it will be possible take the pistons complete with rods from the top of the barrel.
My guess is then an engineering shop would be your best option for the offending barrel complete with top case.
Good luck my friend