the problem with healing is technically you dont need it to do the main content, and healing in a solo build reduces your dps making it take longer to kill stuff..
But the best direct healing is blood / Fist. This is probably what your aiming for mid game (Blue mountain & early egypt)
Actives:
Cauterize
Surgical Steel
Empathy
Blood Shield
Angelic Aegis
The Scarlet Arts
Shelter
Passives:
Hot Iron
Healing Sparks
Out of the Woods (Elite Passive)
Brawler (Hammer 1 AP passive)
Rapid Shield
Angel�s Touch
Glyph for Crit rating (aim for 700-800), Crit Power (400-500) dont bother with penetration, you not goign to be hitting stuff, and heal rating instead of attack rating. But with this build you wont solo anything, its a pure heal/support role.
oh and yes there is a spare passive slot. You can slot it with anything that will boost your healing sensibly.