From the look of the pictures the oil that is in the engine is oxidized, normal when things sit for years.
You do need to have torn down, cleaned and renewed just to get the old gummy oil and gas mix out of there, and nice clean stuff.
Oils now are much better, you will have nice long life as long as you ride it regular.
Wait until you see the fork oil!!! And the wheel bearings, steering bearings, and swingarm bearings.