I think this would work, but only a dev could confirm it.
Add a pop up box like Fire Shield and Delayed Blast Fireball have, with two icons: one for a ray version that does damage, and one for a "cure" like cast (close range, like the clerics cure spells). That way the two versions could have different "damage dealt", as they would basically be two different spells. You could have decent damage for the ray version that would also allow metamagics to be applied to it, and lower the "damage" for the "heal undead friend/self" version to keep it balanced without the metamagics.