smoking Briggs motor (help )

[renovation]

i just checked out my 17 hp Briggs riding mower .
the motor started smoking a bit ago. i did a oil change and that cured it for a while. now again it started smoking again .last time i found it to be way over on the oil and it smalled like gas. this time i just looked at the dip stick and its not showing its over filled but I'm getting a heavy smell of gas on the dip stick.
also the muffler is covered with black burned oil .on the muffler it self and on like 1/4-1/3 up the tube running from the block down.

I'm thinking the rings are toast is my problem any other ideas !
the rider is only 5 years old and it has a 17.5 hp Briggs Intek™ Series motor on it . link to motor - http://www.briggsandstratton.com/eng...ls.aspx?pid=29
i pulled a parts list and diagram for the motor looking for a (pcv) breather/ vent unit and didn't see one or anything that looked like a motor vent (pcv).
if someone with more knowledge on these motors. could check out the motor break down to see if they see if there is a vent or unit i sure use the help . im not wanting to rebuild the unit if i dont have to . i priced out a short block and they want $450 or $900 for a long block
model 31c707 type 0154E1 code 050202A

[Prngr44]

See if you can't get it on that electronic cigarette to help stop smoking.