'Took a bit of a risk, but tried something I've used on filthy alloy wheels in the past...OVEN CLEANER.

Warmed engine for ~20 mins, donned vinyl gloves (stuff is caustic!), then applied a light stream of oven cleaner directly onto the metal parts which had the dried oil coating...agitated lightly with an old paint brush...then let it sit for about a half hour.

Rinsed with water in a gallon jug and brushed off using the same paint brush...the ugly stuff sort of rolled up like rubber cement, leaving a clean surface. Later, I was even able to sweep up all the little dried bits which fell to the ground.

Maybe a tad anal, but now I'll be able to quickly assess engine and hose condition, and spot any leaks which develop.