here is what i did. i stole the parts (four caster wheels) off of a furniture dolly and made this. some scrap 2x4's, and a piece of cal-osha approved walkway planking (way overkill, but basically a 2x10). i do have the advantage of a low-profile floorjack.
when you lower (or raise) the motor, it drops down on the casters and you roll the motor out. it has done maybe 12 engine drops. works great!