From BG Wiki
Healing Magic Skill acts as a multiplier.
One MND is equivalent to three VIT or five Healing Magic Skill.
1 MND is equal to 1.5 HP and 1 VIT is equal to 0.5 HP.
See the cure formula page for more details.
You may already be at the hard cap though. Prioritizing auto-refresh may be more beneficial. It would take 14 points for a 1 tic refresh but if you've already set everything else why not. Sadly my RUNs master lvl isn't that high and I'm too lazy to do the calculations :)