Of course I can help you and your father, sweetie. I've got three options for you.
1) I can just take his curse away and make him mortal and normal with no consequences, other than he'd be a man of normal middle age, with all the trappings of mortality.
2) I can halt the curse for the time being, keeping him in his regular state as you've suggested, then giving it back to him when he can take souls again.
3) I can make it so that he still takes souls, he just doesn't cause harm to the person. Not everyone needs a soul to live. He can take them from people who can survive without them. I'll email him a list.