Well... "canonically" they're mounted on the forward section of Deck Three in the upper "bulge". Non-canonically, I once saw a fan illustration that showed a double torpedo turret mounted between the forward phasers, just above the lower sensor dome.
I just read this message from Thomas Sasser, who's working on the tooling:
The base on this kit was part of the initial design process and not a last second addition. The intended base is very unique and fitting to this model and was conceived by Mr. Shane Johnson. If all goes as planned, even the base will have decals! It is basicaly a cradle to hold the model up and not on a post. I also incorporated a feature into two of the cradle arms that will be cast in clear and will become very useful for anyone attempting to build a cutaway. Of course you'd have to come up with another base then....
The Ertl refit kit has weight sag issues due to the fact that the nacelle pylons are about half as thick as they should be, with thin flimsy tabs to hold things up at the structurally weakest point. The top of the neck on that kit is also not contoured correctly to mate with the saucer to hold it up straight. I've spent the past 6 months drafting tooling plans, going over hundreds of images, specs supplied by Mr. Gary Kerrrrrrrr! and speaking with VFX artists and getting their input. I don't think you'll be disappointed with the overall shapes, contours, proportions, or assembly of this kit.
This kind of reminds me of an email I received from a guy before the release of the 11" 1701 kit after he saw the pictures of the mock up. He wanted to know how Polar intended to keep the center span between the nacelle pylons from bowing up and the pylons from spreading out under the weight of the nacelles! C'mon! It's a plastic toy, not a 900,000 metric ton vessel!