Good detective work! I see you're dealing with a late model 235 without the dippers on the bottom of the rods, so the pan should be pretty open. Earlier engines had a trough under each rod for the dipper to dunk into. Scrape out as much crud as you can from the oil pan then grab a stiff-bristled parts washing brush and some solvent like kerosene, mineral spirits, or one of the water-soluble cleaners, and give toe pan a good scrubbing, inside and out. Follow up with a pressure washer or take a trip to the local coin car wash for a pressure blast with the tire cleaner/engine degreaser. Some car wash managers frown on this so I usually do my engine block and cylinder head cleanup LATE at night!

There's a really good way to use the engine itself as a degreaser for the crankcase- - - -after reinstalling the pan, fill the engine with cheap 30 weight oil, and add 2-3 quarts of kerosene or Diesel fuel over the full mark so the crankshaft is whipping into the oil/solvent mixture. Run the engine at a fast idle, maybe 1,000-1,200 RPM for about 10 minutes.

DO NOT DRIVE THE VEHICLE OR PUT ANY LOAD ON THE ENGINE!

The crankshaft will do an excellent job of splashing the solvent around, and if you drain the crankcase while the mixture is hot, the sludge will drain out with the oil. Refill with your usual engine oil, change the filter cartridge, and drive on!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!