Exactly so. That plug was called an acorn (in Britain) because of its shape. Loco 303, in the linked image, has the British style coupling arrangement. Nothing wrong with it, but it is not Eames. The advantage of the acorn is that it retains the hose in position as well as sealing off the vacuum.
Our loco 9 has the Eames driver brake in largely original form (except no muffler). The Eames installation on loco 9 is an important piece of technological heritage that would be found in very few places, elsewhere.
The idea of fitting continuous vacuum brakes to WWF trains will necessarily take us away from the original configuration of the rolling stock not only because it was not there, in the beginning, but also because of the need to interoperate with the existing equipment on loco 9. I am sure that our people are well aware and sensitive to all that but I have failed, so far, to have any meaningful input to the development of the proposed continuous vacuum brake system. We are told, however (Board minutes, etc.) that development work is in progress.
The introduction of close-able cocks is a safety hazard, apart from being unnecessary and non-original. The Eames coupling had a hinged flap-type stopper to retain the vacuum. These flaps swung aside when hoses were coupled.
The Eames control valve, in the cab, was highly idiosyncratic - a most interesting piece of equipment. I have no idea whether any attempt is being made to be true to Eames in respect of that. I do suspect that rather modern valving is being hidden away beneath the cab floor.
My desire is always that an observant and knowledgeable visitor to the museum will learn the truth. We don't want people being deceived.