I know you have said safety is paramount but as myself, Croppie and others have said, moving the boiler is the only way. A plume kit, periscope or whatever you want to call it is a no go.
You need to post on the Looking for an engineer section or get your own GSR engineer out to advise further as us looking at pictures on this thread isn't going to get your boiler moved.
You need to post on the Looking for an engineer section or get your own GSR engineer out to advise further as us looking at pictures on this thread isn't going to get your boiler moved.