Looks like it would fit perfectly... The PCI slot on the mobo is supposed to be on the top of the back i/o slot. I promise 100% that you can fit a reasonably sized graphics card in there. Might be too short for some of the really high end cards; I can't tell. I can tell you, however, that you will have no problem whatsoever with the alignment.
FYI you can get a 6450 for like $30 after rebate on Newegg, in case you're interested...http://www.newegg.com/Product/Product.aspx?Item=N82E16814150581
$23 shipped after rebate