Re: I'll do that, _____ if you want
I don't find any of your suggestions natural.
I would have done that if you had wanted me to. (Past - you didn't do it.)
I would do that if you ever wanted me to. (Future for the whole thing.)
I will do that if you want me to. (Future "will do" and present "if you want me to".)
I don't know why you want to incorporate "even" into the sentence at all. That would only be appropriate in the negative: "I would not do that even if you wanted me to".
Remember - correct capitalisation, punctuation and spacing make posts much easier to read.