The design would not work very well as a beetle weight. Your speed is still way too low, and now is even more of a detriment as the beetles are even faster and tougher. You really need to up the wheel size(2.25" to 2.5"), as the wheel size is . Build to one or the other, because Sumo and Combat requirements are very different.
Also, while ballasts would help keep the bot low, building lower would be even better. Lower is always better, unless the design mandates the machine to be built tall.
You could run the motor above with the ESC(Maybe, I can't find a reliable source that says how much current the ESC can take), but a
bigger motor more suitable for the weight class and a higher current
esc would be even better.