If the holes do not line up, you should still be able to pull it off with careful measurements. If you can get the engine positioned so that the shaft ends up in the original location, you would just have to drill new mounting holes. If not, you may have to mess with belt sizes.
you can put anything you want on it.. its just a matter of measuring and fabricating. make sure the output pully is centered as the old one was, and you'll be set. if it dont line up, fab up some motor mounts. having to center everything will be a PITA, but can be done