Instead of the Ardent Censer you could make Redemption, this however does NOT give you AP or attackspeed to your allies when you heal.
Depending what you're up against, decide if you go for Spellthief's Edge or Ancient Coin in the beginning. Generally, I start with a Coin instead of Spellthief's, because the Talisman of Ascension really comes in handy in teamfights; when you have to flee, initiate or catch up to someone.
After making all this you see in the build, go for an AP item. It will boost your healing power so people will be grateful to you for that.
You might also consider making Cooldown Reduction as last item, or maybe even CDR boots instead of Boots of Swiftness. This ofc depends on personal preference.