Hi Best buy has the previous gen 27" iMac on sale with 1TBHD for 1299, 1TB Fusion HD for $1499 and 2TB Fusion HD $1799. I really like the 27" screen but want to modify the HD. I would like to add an SSD and upgrade the storage HD To 3tb+. I wanted to know is this possible with these or am I out of options? If it is possible, which model would be the best to make these additions to. Thanks.