Bill...by the looks of your sparkplugs..its probably a leaking head gasket..look closely at the area between the oildrain hole and the cylinder..the reed valves are located between the lifters on the block.
You probably didn't have any blowby....if you remove any dipstick while the engine is running..its gonna blow oil out...when you took out the dipstick...you lost all your crankcase vacuum . It takes a special vacuum gauge to check crankcase vacuum..
One more thing to check...was there a lot of buildup on the pistons?
If so...move the piston to the top of the bore and see how much flop you have in the rings..push in on the top and bottom of the piston...
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