It seems Paramount didn't mind nacelles under the saucer- the Miranda and Nebula classes.
Not in TOS though. apparently the shielding got better in TMP, even for the Klingons. The BoP had internal warp and an all Klingon crew.
I didn't invent the idea of the nacelles being too close on the Burke-class, BTW. I just agree with it.

P.S. A matter of scale? What size is it? The same size saucer as a TOS Connie?