None of the themes allow you to move things like this. As noted above, you would need to modify the theme to achieve this - meaning you would need to buy the custom CSS upgrade, learn CSS (the hard bit) and then modify the theme.
Just FYI - Tarski (which I also use) has one thing that bugged the heck out of me - the position of the comments and the comments input box. If you do buy the CSS upgrade (which I have) I would suggest adding the following in to correct this:
The USD10 for the upgrade was worth it just for that.