I would strongly urge you to drop the pan. A 216 has troughs where the dippers on the connecting rod scoop up oil to lube the bearings. With as much sludge as you have described, I would not want to risk running this engine on scooped up sludge, not even at idle.

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission