Normally notch the rear for oil pan clearance if needed. Once you get it really clean, check for any cracks and redo any factory welding that looks a bit ropey. I sometimes bend up a bit of rod and weld it to the front to use as a towing eye or trailer hold down. Cut off all the engine mounts if you are using a motor plate. Do a bit of careful grinding to tidy it up a bit. It's a main structural component so I wouldn't unleash the hole saw on it....