Christopher - as far at the refit goes, it mostly gets a bonus in terms of "squinting (not least because we saw so little of it). However, in the case of TOS the engine tubes were mis-photographed so many times that we really have little choice but to interpret them as part of a short triangular wedge-shaped engine component, rather than the long structure they were originally intended to represent.
Of course we have a choice. As I already said, that's where our imagination comes in. We're pretending a set on a soundstage in Hollywood is the engine room of a starship, we're pretending that actors we recognize are people living centuries in the future, so we can just as easily pretend that the tapering pipes actually do stretch as far back as we're intended to believe they are.