70%?!
What are you saving it for?
They rarely go hard enough to shut off mine at 35%.
The way free flags are designed is that your vote value doesn't go down until you run out of downvote mana and start using real votes.
So, even back before the split when we flagged alot rarely did I get taken below 35%, 25% might be safe, I have another account set to that and haven't noticed any problems.
Unless you just want to do it manually.