Honestly you should either buff or delete spell vamp tunes entirely

In their current state they are garbage because theres no current way to increase your potential camp outside of masteries. Even isn't considered spell vamp anymore. I can see them having niche uses, especially for champions with health costs. I know you don't like runes influencing the game too much but you're making a pretty big sacrifice to run even 2 spell vamp runes in exchange for something like AP

If not, just remove them and compensate all owners by returning the 6k+ IP they invested in them. Either way, they aren't good right now.