What about 32/0/5 at lvl 46 ? That way you can still do lots of dmg and have more sustain from spirit and mana regen in Discipline tree. Also, healing will be easier in dungeons when you are nearing lvl 50. Talent spread at 46: (http://db.vanillagaming.org/?talent#bVMusVVqoZx)'
After this you just work your way down the holy tree gaining some more dmg out of smite/holy fire and more crit effect out of holy spells. With this spec you also get some nice cooldowns so you can burn high hp mobs/clothies in PvP.
Ofcourse this spec will be worthless at 60 but may be abit fun to try out if you are bored with shadow leveling :)
Edit: That said, Shadow is very strong in the 40's so might want to keep onto that ^^
