This is not what I think the TOS should look like. But more like what the TOS Enterprise would look like if it resembled the Movie refit Enterprise prior to it's refit.
My idea is that the saucer was expanded, new bridge module, new nacelles and pylons. New hull plating and the deflector dish plated over. Something I think that would fall in line with a 18 month refit.
Here is the comparison:
TOS Enterprise Revised
TOS Enterprise Revised
"Don't underestimate the power of technobabble: the Federation can win anything with the sheer force of bullshit"