On the zilla motor you have to fix the case journals, rechamber the head, upgrade the studs, watch the flywheel and reinforce the cylinder if u port it to get good power and make it reliable. Not to mention a custom pipe from one of the zilla gurus will cost 500 to 1000 and pray you can make 75 HP. For that kind of money I can buy anyone of the cheetah line of cylinders and match the zillas torque and it will be easier to kick start.