While possible, it would take quite a bit of css tweaks to get working with the same level of support the current layout has. You'll need to change the css container for each of the various layout types in includes>format-(postype).php . So in format-standard.php you can see the css block for the meta info which is inside a three unit grid and the post content inside a six unit grid.
You would need to move everything in the meta info div, remove the grid class from that block and perhaps add a new one that floats left. Then change the content div class from six to nine so that it takes up the whole width.
If you are comfortable with CSS/HTML it may only take a few hours or a day to get everything re-structured to the way you want it.