I managed to get the sand pipes fitted and then moved on to fitting the motor to the chassis and testing within the body.
On this there is good news in that I should be able to squeeze in the brake cylinder albeit that to avoid the plunger pickup I will have to fit it to the rear of the frame spacer instead of the front but at least it will be there.
Then there is bad news. Brian has provided a really nice ABC motor/gearbox unit. Sadly, the kit is designed for a can motor with simple gears mounted to a frame spacer. The motor gear box will fit into the boiler area no problem but where it does cause an issue is that it interferes with the rear brake cross beam which I think I am going to have to cut.