That is weird,you can drop the steel front pan easily for a quick look inside. I wonder if the oil pump drive seized for some strange reason? Normally an engine explosion goes out ,not sucked in like that .
regarding the above statement about 4.5 subframes,all W108-W109 -W110-W111-W112 and W113 use exactly the same from axle assembly .No need to change or cut any part of the car to fit a M110 into a W111. Some trans need a clearance lump welded into the tunnel above the Flex disc but it a minor job.