You should consider the Intel® Ethernet Server Adapter X520-LR1, E10G41BFLR. This is a single-port adapter that comes with an optical module installed that supports dual rate 10GBASE-LR/1000BASE-LX. As a bonus you will already have 10-gigabit capability if you want it later.
Another option to consider would be to get an Intel® Ethernet Server Adapter X520-DA2, E10G42BTDA, without any optical modules installed. You could buy the Intel® Ethernet SFP+ LR Optics, E10GSFPLR, for the port you wanted to use for LX, and then have a left-over 10-gigabit port that you could use for either direct attach or buy an opitcal module for that port too.
Check out Which SFP+ modules, SFP modules, and cables can I use with the X520 Series? for more details on what you can do.
I hope this helps.