Heey 63 hours rendering you say, this look more like a 63 min rendering too me. Im sorry but thats WAY too long for this scene. Its grinny and looks like sample level 13-14. A better light setup might decreas alot of time for you mate.
ya, dont know.... 63hr seems a bit long to me, so only physical sky u use?
what is the sampling level? are u using beta 1.2.1? it shouldn't be that grainy.