340 Duster oil looks milky

If the oil hasn't emulsified with whatever may be in the pan it will stratify...separate...and as oil is lighter than water or coolant mixture or whatever might be in there, however small the amount, the oil on the dipstick will look better over time if the engine hasn't been run. The coolant level wouldn't change if it hasn't been run. No pressure or flow if you're thinking head gasket, especially if it's very small.
Is that a newly rebuilt engine that's been broken in?
Welcome...BTW