I've taken two Kaplan CATs, one within the last 36hrs and score 730 & 700 respectively. My posts are a few threads below yours. I'll also be taking the GMAT today in less than 12 hours so I'll update tonight or tomorrow once I know my score to give a comparison btwn actual and Kaplan scores. (I scheduled a 6pm test and its 6am over here...)
I find that the Math score is not indicative of much. The Kaplan math section tests you only on the grasp of the basics and the DS qtns are insufficiently challenging. You rarely find difficult conceptual qtns such as hard inequalities DS questions that frequenlty pop up on Gmatprep. You should take a high score here with a pinch of salt.
Because of the scoring algo which punishes careless mistakes very harshly (since the low difficulty level will result in a high score penalization with each question wrong), a low score doesn't count for much as well. You should only be worried if you are getting the qtns wrong because they are too difficult for you which in your case I find unlikely. Be careful, your 46Q prob means you tend to make careless mistakes. If you have timing issues in this test with this level of difficulty, I would suggest strongly that you improve your time management as GMAT qtns I assume would be at a much more higher difficulty level.
Verbal is a mixed bag. RC can follow a huge range with very difficult or very easy passages to delve through. If you do well in the difficult ones, you should be pretty much set for RC questions on GMATprep. CR is pretty straightforward as well. SC is very different from what appears on the GMATprep in my opinion with many qtns not following 2/3 splits. Also, the scoring algo punishes wrong answers very severely as well. Because of the weird algo and varying difficulty level, I've noticed from the scores of other posters in this forum that their verbal Kaplan scores jump around enormously. If you can consistently score high for verbal in Kaplan, I think you should do well in the actual exam as well. If your score is all over the place, than you can't really draw a conclusion one way or another.
However, reading other posters, none of the other companies, Veritas/Knewton/Manhattan, really come close to replicating the GMAT, so use these tests to improve your timing and test taking skills. If you consistently score well and can get at least a 50% on the toughest conceptual quant qtns (within 3 minutes), you should do very well.
Good luck!