The bank of four seats may get removed, maybe. Don't forget this picture is not a fully kitted out SAR cab.
I am sure you are aware the 139 has a tunnel through to the boot where they stow the stretchers and other kit.
All the kit mentioned to be carried is currently carried and properly stowed in the 139 which is smaller so I cannot see what the problem is.
As far as maps etc to be carried then I am not sure whether a full set (aviation and OS) will be carried but don't forget we must forward in technology and having a full mapping system both in the front and back to OS level will be provided.