You can use an auro 3d layout for atmos NP and move your rear surrounds to height duties as I did. I know you don't have auro3d, the layout is all you need though:
http://www.stormaudio.com/media/white_paper__combined_auro3d_and_dolby_a...
Q I own a Denon AVR-S920W AV receiver. The Denon has a 7.1-channel speaker output, and two of the speakers can be assigned as either Surround Back, Front Height, Top Front, or Top Middle. Until now I’ve run a standard 7.1 system with surround back speakers that, due to room limitations, are positioned close to the ceiling. But the AVR-S920W also has Dolby Atmos and DTS:X processing, and I’m now interested in reconfiguring my speaker setup for object-based audio. Should I leave the surround back speakers in place, or set them up as height speakers? —Michael Welters
A While DTS:X is an object-based audio format that can scale to pretty much any speaker configuration, your current setup included, Dolby has fairly rigid recommendations on how speakers should be positioned for optimal reproduction of height effects with object-based Atmos soundtracks.
Denon’s manual for the AVR-S920W is fuzzy on the topic of how to set up speakers for Atmos, but the company appears to recommend three height effect speaker configuration options: Front Height positioned close to the ceiling at the front of the room; Top Front installed in-ceiling and in line with the main speakers in front of the seating area; Top Middle installed in-ceiling and in line with the main speakers directly above the seating area. Another option is to use upfiring Dolby Atmos-enabled speakers at either the left/right front or left/right surround speaker positions.
Dolby’s recommendation for a 5.1.2 Atmos setup (five main speakers plus subwoofer and two height effect speakers) would have you use in-ceiling speakers installed in a Top Middle configuration, or Atmos-enabled speakers located at the left/right front positions with your Denon receiver. Either of those options would require buying new speakers, however.
If your plan is to repurpose your current surround back speakers, you could connect them to the receiver’s Top Middle speaker outputs, with the speakers installed near the ceiling at either side of the listening area and angled downward. This setup is similar to one touted by speaker-maker SVS for Atmos installations where in-ceiling height speakers aren’t convenient. Another option would be to configure them as Front Heights according to the recommendation in Denon’s manual, with the speaker’s front baffle angled down toward the listening area. If neither works to your satisfaction, consider getting new speakers and going the Dolby-recommended route.
You can use an auro 3d layout for atmos NP and move your rear surrounds to height duties as I did. I know you don't have auro3d, the layout is all you need though:
http://www.stormaudio.com/media/white_paper__combined_auro3d_and_dolby_a...
I decided to repurpose and reposition the rear satellite speakers to front up-firing speakers, effectively going from 7.1 to 5.1.2. I was impressed enough with the immersiveness that I finally shelled out for Dolby Atmos Enabled up-firing speakers (Onkyo SKH-410s), since they are purposely designed for the bounce-of-ceiling effect and apparently have special circuitry that is necessary for them to qualify for the official Dolby Atmos Enabled tag yet are reasonably priced. They are a definite improvement over repurposing/repositioning rear satellite speakers in an upfiring position (though that did work). Now I want to put my rear satellites back in a rear height position, get a 9-channel receiver, and implement a 5.1.4 set-up. As more and more Netflix material is Dolby Atmos enabled, it is starting to look worthwhile. A couple years ago there just wasn't enough source material to bother.
Although a bit old need to comment on this.. Uplifting speakers will NOT improve the ATMOS sound.. ATMOS needs to have the speakers at height well above the listeners ears. So Repurposing surround speakers will provide MUCH better ATMOS sound than a pair (wast of money) upfiring speakers..
Well done for falling for another pointless AV money trap the manafacturers want you to believe..
There are plenty of posts supporting the repurposing of satellite speakers for atmos speakers..