don't rebore la... not worth it... so much money spent for extra 100cc and kill your reliability =p AT least to me its not worth it la... workmanship is not cheap to rebuild engine, you're better off shoving in a 4G92P block from chopshop. Prob cheaper and u gain more power from the higher compression pistons. =p But on the other hand, the 4G91 head on a 4G92 block also not to say super reliable. The gasket will leak, just a matter how when only. =p Metal gasket of course can last longer.
Lighten crank pulley is a good way to begin. You should feel better engine response from that.