The BH20N is an OEM version of the BH08NS20 and yes you can crossflash your BH20N to its LG retail equivalent.
The problem is that the latest available retail firmware for the BH08NS20 is 2.00 (released 2009-10-31) which is still quite old.
What you could do instead, is to crossflash your BH20N to a BH08LS20, for which a newer firmware is available (v2.00-03 released 2011-05-02). Such crossflash will not enable Lightscribe (as unlike L/LS drives, the N/NS drives do not have the necessary hardware for it to work), but at least you'll be able to take advantage of the newer firmware which has better media support than version 2.00 for BH08NS20.
In order to crossflash your drive, load the firmware in MCSE, tick the relevant boxes you want (increase speed, auto RPC2) and then press save. That will create a new crossflash ready 'speedpatched' file. Use this 'speedpatched' file to crossflash your drive. Turn off your computer (just restarting might not do the trick as not all mobos cut off the power to optical drives during a simple restart, and LG drives need this) and on restart your drive should identify as a BH08LS20.