wht if i made the combustion chambers in the rotor shallower biasing the depth towards the front of the combustion chamber

You decrease the volume to surface area ratio making a bad combustion chamber shape even worse. You also increase the compression ratio. 10.0:1 in the renesis has long been considered the high limit for a practical compression ratio, and even then, the gains just arent there over the 9.7:1 rotors.