Weights on 75 gallon water heaters are in the 240-300lbs range- roughly 2x or more than the heft of a 40 gallon unit (120-140lbs). Been working out?
If it's all level ground and you have an adequate hand truck for moving it around you may be able to get it into place. I managed to get a ~325lb reverse-indirect HW heater into my house down 8 concrete steps to the basement door off the driveway by myself, but that took some ramp-design and a rigging a belaying system, and couple of hours of figuring it out. (You may not be as crazy as I am. :-) ) Getting it out would be a bit tougher than getting it in.