is not a very good indicator of your actual GMAT performance. Math section is tough, but you can expect 80% of that toughness level in GMAT. Verbal is very different -- and does not represent GMAT at all. You can probably add 80-100 to your Kaplan
score to reflect something close to GMAT score.
Dont get disheartened, you may want to take Princeton Review
test -- its a good reflection of GMAT levels (Verbal is little easy though).