Lawn mower motor

[vossman]

Picked up non running mower with a decent Briggs and Stratton motor. Guy I got it from somehow overfilled the oil, I took about 36oz out of it and it probably needs about 18-20oz at the most.
The muffler was filled with oil, spark plug was nasty, oil pushed back through the carb and into the gas tank I think as the fuel was black and oily too.
So, I took the muffler, carb, linkage and gas tank off, cleaned them up. Looked inside the spark plug hole and the piston looked nasty dirty and oily.
Should I try to flush the piston area out with fuel or carb cleaner to clean out a bit of the oil before reassembling? I don't wanna take the head off if I don't have to. I don't have any oil in it now asi wanted to flush it.
Any advice is appreciated.