Most efficient way to adapt current mockups to different devices and resolutions

Ok, so I've completed about 90 screens of mockups in Photoshop for an app. The mockups are done for iPhone 5 / iOS7 (640px by 1136px). Everything is calculated to pixel-perfection.

Now, management wants to see the mockups on iPhone 3GS / iOS6, iPhone 4 and iPhone 6, as well as how it will look like for Android devices.

The normal way is to go back to Photoshop and create a new set of 90 screens and re-adjust/position everything for iPhone 3GS, iPhone 4, iPhone 6, and then for Android-based systems, that means I need to do mockups for Samsung Galaxy Note II, Nokia Lumia, Windows Phone, HTC and 750 other types of phones out there.

Now, doing and documenting 90 screens alone took like 3 - 4 full weeks....THERE'S NO WAY IN HELL (nor is there time) to do for all phones.

So, with my current iPhone 5 mockups, is there any quick way to re-adjust it to most of the devices asap? Or is it actually easier for the dev team side to fix this?

Need some advice. Tks!