Huh? RCA, why do you think this comes across as a TNG-era refit? I'd think of it more as an alternate pre-TMP ... emphasis on the "alternate".
I enjoy the various ways that people try to fit these designs into a logical progression of eras - they used to classify them that way in the download area of 3DW, and mine would wind up all over the map. I really give no particular thought to that when I build one.
There are various details that I carried forward from the TOS ship - but then, so did Church.