Top Heavy Table Tennis Rackets

Use cybershape with 2mm to max sponge rubbers

This is also tricky because of the weight of the rubbers.  Some rubbers weight more than others.  I lost over 10 grams when I switched from Yasaka Rakza 7 to Yasaka Rakza 7 Soft.  The weight of the rubbers will make the bats more top heavy.

Generally,unless you use two very thin rubbers,ALL bats are top heavy.
If you want to find out,try to balance a blade on your finger or a stick with your finger under the bottom of the blade (the place between the "rubber" and the handle.
If the bat falls on the handle's side,it is NOT top heavy.
Given the general physics,I heavily doubt there is any bat which will fall towards the handle.
The volume of wood in the blade area is always bigger and as far as I know.

The ratio of weight can be also estimated by comparing the blade-handle size ratio.
Blades with large head compared to their handle will be more top heavy.
This majorly includes anatomic handle blades (yes,the very same blade can vary its weight distribution depending on its handle).
Also,try to find blades using Senso technology and similar.
Senso blades have hollow handle,which makes the handle much lighter.

I agree with Alois, the only reliable way to tell is to hold a racket with rubbers in your hands. Depends entirely on how it feels for you. So, go try and hold as many as you can with other people's rackets, with their permission of course. :)

To add a bit more of my personal experience. Around 10+ years ago, I bought the Timo Boll Spirit blade as I was a beginner at the time and a bit of an equipment junkie (I must admit). The blade doesn't look top heavy at first and was surprised that when I used it for several years, my wrist always hurts or at least uncomfortable when I do a backhand stroke. I only learned recently from a TTD video with Timo on it, that he likes top heavy rackets that's why he also has a straight handle to move the center of gravity towards the top.
So, if you like top heavy blades, you may also check other players who likes it that way. 

On another note, I learned the hard way the equipment doesn't make you good at table tennis. Proper technique, lots of practice, and tournament experience does. So, go practice, play with lots of people, get coaching if you must and of all have fun :) You'll find what you need along the way.