Using elephants as towers seems a little strange seeing how towers have such a longe range. I'd consider chariots.
Bishops could be cavalry due to their fast movement and the way they are used to outflank.
Knights could be warriors or maybe auxilia infantry.
Also, you have your board set up the wrong way, Kings and Queens are opposite each other. Also, it would help to distinguish during a game of chess whose side a piece is on so sticking with one color of blocks per side is helpful too.