Was thinking similar myself. There's a shapeways body for the JT class available too. Wonder if the Bachmann tank would be suitable as a chassis donor? Think'd I'd have a bash sorting the cab out instead to guarantee a nicer finish.
Agreed, the Lima models don't have the distinctive interior. Sell the exec coaches and for the price you'd nearly get enough for a whole BR Mark 3 rake to convert, including your Exec coach.
Just think of the whopper layout and stock you will be able to afford should you do well in exams and get good jobs lads. Might even know someone who could get you into IE and live the dream and get paid for doing so!
Has anyone done any of the blue cravens yet? Don't think I've seen them modelled. Not a fan of the real livery but a preserved current RPSI craven rake would make an interesting model.