Many S5 features depend on its framework, which is surprisingly hard to port. If you want to rush it, maybe we can have a look-alike ROM with 70% similarity in looks but 10% similarity in function - not what you wanted, yes?
Besides, you outta buy a S3 or S4 because they have a much better chance of having S5's ROM ported. Galaxy Nexus is born for AOSP
Sent from Google Nexus 4 @ CM11
Google Nexus 4 (CM11 Nightly)
Motorola Droid RAZR M (CM11 Nightly for JB BL)
Sony Xperia SP (CM11 Nightly)
Google Nexus 7 (2013, WiFi) (CM11 Nightly)
Samsung Galaxy Gear (Null_ Build 23)
Samsung Galaxy S WiFi 4.0 (CM10.2 Unofficial
Nokia N86 8MP (RM-484 30.009 Pre-Hacked)
Multi-core smartphones are like M&Ms:
They don't melt on the store shelf... Just in your hands.