I'm not sure how the SB-LM can give you more accurate results when it was last normed in 1972.

The differences are likely to be substantial, not because the "real" IQ is different between the tests, but rather because the LM uses a different method of calculating IQ numbers that modern tests don't use, and because a test without valid current norms doesn't give accurate numbers. The SB-LM generates wildly high numbers that are quite different than current test editions.

Is there anyone besides the GDC still using this test?