First, be aware that for certain colleges, you are required to submit all scores for all subject tests you have taken, see http://talk.collegeconfidential.com/sat-act-tests-test-preparation/1912440-must-you-submit-all-sat-act-or-sat-subject-test-scores-p1.html
Second, there are some colleges that require subject tests for admissiion and they all require two. Thus, for those you must submit a test other than just the math 2. Personal view is that your literature score is fine to submit to those colleges. Those college generally use the highest two scores if you submit more than two and thus you do not really have a downside sending all three even if your Japenese score turns out to be higher(or lower) than 740.
Third, there are a number of colleges that recommend subject tests and they typically recommend two, except Georgetown strongly recommends three. For Georgewtown, you better be prepared to submit alll three subject tests. For others that recommend, many of those consider the highest two but some are like Harvard and Princeton, which say they will focus mainly on highest two but will consider any sent. But again I perceive no harm in sending the 740 literature. However, for those you might want to wait and see what the Japanese score actually is before deciding to send it.