Unfortunately that is not possible. Sw can't be derived from mass and and balance alone.
By the way, I found the links I mentioned in this thread back in 8/2012. Greg Raven's Site has the Swingweight for Andy's racquet from the 2009 BNP Paribas listed as sw
404. It's also noted in his stringers notes that digit is unconfirmed, so I suppose we will have to guess at the meaning of that asterisk in the ledger.
Greg also has a second listing for Murray's racquet from a Challenger Event (so it's fairly early in his career) as
357 grams, balance at 34.0cm, and sw 418. I would have guessed 365-380. 404-418 is at the high end for sure, but not all that freakish I suppose. Gasquet was listed at sw 381 in 2009, Marion Bartoli at 394 in 2012, Elena Dokic at 383 in 2009, Soderling at 392 in 2010, JM Gambill at 393, Taylor Dent at sw 400 in 2004, and Carlos Moya swung 405 back in 2001.
2009 BNP Paribas Open Stringer's Log:
http://www.hdtennis.com/grs/pro_racquet_specs/2009bnp_paribas_open.html
Grab Bag Of Legacy Specs:
http://www.hdtennis.com/grs/pro_racquet_specs/grab_bag.html
-Jack