Here you can find all modded kernels.
The numbers are speeds for CPU, GPU, DDR.
kernel104_cpustock_gpu798h_ddr720.img
kernel104_cpustock_gpustock_ddr720.img
kernel106_cpu1608h_gpu600h_ddr600.img
kernel106_cpustock_gpu798h_ddr720.img
kernel106_cpustock_gpustock_ddr720.img
kernel_Cube_U39GT_Stock_1.04.img
kernel_Cube_U39GT_Stock_1.06.img
YOU CAN TRY ANY OF THEM, BUT I RECOMMEND THIS ONE:
It is based on 1.06 with stock clocks, no overvoltage, just less steppings for the speeds.