Well a friend of mine works at the Library of Congress and was able to give me a bit of information (that is all publically available) about the films and what exactly the LoC has. She was also able to give me some information on copyrights.
Basically if you go to http://catalog.loc.gov and do a basic search. Search for 96512247 using the search type LCCN-ISBN-ISSN you should get the the entry for Star Wars and if you click on 'Full Record' you will get all the information.
Basically what this tells us is that the LoC does have a copy of the original film reel (as was expected) and that this appears to be the '77 version. My friend told me that the online copyright database only contains works registered on or after 1/1/1978 so the film was copyrighted May 25 1977 which makes sense, but we cant search that record.
So if we look down at the Source of Acquisition information we see 5 entires. the first three appear to be laserdiscs from the 80's these are the viewing copies so it would seem that the viewing copies are going to contain the updated scroll since thats whats on the laserdiscs.
The other 2 copies they have are listed as ref. copies which are the archival copies and as my friend stated, 'you probably can't watch them' but looking at the dates these reels seem to be the original versions.
Now, some information not on the page my friend gave me is that the LoC (generally) recieves (at least) 2 copies of the work. one copy is made available for viewing and the other (the one in better condition) is put in hi-tech format specific storage. She also said (this came up in another thread) that they dont actually let you 'touch' the viewing copy and that basically you can just watch it in a small viewing room and it would not be possible to aquire scans of the actual film.
So basically this is a good news, bad news type thing. Good: Even if Lucas no longer has a copy of the Original Film the Library of Congress appears to have one (that is also probably stored better, and thus in better condition, than any copy that Lucasfilm has) Bad: But we wont ever see this copy as its for Archival purposes.
"Anakin, You're father I am" - Yoda
"No. No. That's not true! That's impossible!" - Anakin
*touchy people disclaimer*
some or all of the above comments are partially exaggerated to convey a point, none of the comments are meant as personal attacks on anyone mentioned or reference in the above post