Skids and levers under the mounts help, too. Getting them off the bolts is the difficult part, unless you are lucky enough to have a straight lift upwards.
What is the diesel weight? You know to lessen it (especially if it's permanently leaving the boat) by draining all fluids, removing the flywheel and taking off the alternator and manifold, starter and other accessories, right? Those are heavy pieces and they may be spares for reuse or trade. Hauling out is when they get damaged or do damage to the boat. You want to haul out as "bare" a block as you can easily manage, because it will be lighter, "smoother" and narrower, all the better to go up through the companionway and/or hatch.
The Atomic 4 complete is 300 pounds. The Atomic 4 stripped to a block (but with head and lifting ring) is less than 200. I can manhandle the latter with a hoist and a wrecking bar. The former is going to get pieces bent.