Interesting topic, curiosly enough i find myself in that same situation. You could try Uharc's cls made by Razor12911 as well
http://fileforums.com/showthread.php?t=98005 iirc it overcomes the filesize limit. Regarding compression ratio i still have to find a game in which uharc beats lzma, maybe a precompressor is needed in order to do that or maybe a test in older games.