But if you have Xcode 4 installed you can setup path to SDK 10.7 in Xcode 5
SDKROOT = {path_to_xcode4_SDKs}/MacOSX10.7.sdk
MACOSX_DEPLOYMENT_TARGET = 10.7
MACOSX_DEPLOYMENT_TARGET_i386 = 10.7
MACOSX_DEPLOYMENT_TARGET_x86_64 = 10.7
MACOSX_SDKVERSION = 1070
I'm not sure if you will need to change compiler. But you can check that comparing SDK CC and CC 2014