https://youtube.com/shorts/JjIBINIc4o0?feature=shared

That appears to be engine oil burning from the engine (in the exhaust).
The engine runs good-so I don't believe there's a fuel delivery issue
nor spark issue.  Something inside the combustion chamber is amiss. 
 
Are both plugs getting oily / fouled?
 
It also seems you get much more smoke when de-celling the engine, correct?
 
I'm leaning towards the oil rings being worn (I know you have good compression).
Worn valve seals / guides would cause smoking but more "steady".  
 
The back firing, running crappy, smoke is a result of excess oil in the combustion chamber.
 
Advise on the spark plugs..
 
..

Yes both are fouled.
 
In the video I slowed down the engine at the time it started to surge because it will continually do so at full RPM and the shop would be full of smoke.
 
Thanks

One more thing I forgot to mention.  I pulled the dipstick when the engine was running normally (when cold) and it started pushing out oil out of the tube.  As soon as I did that the surging started to be more pronounced and it was pushing out more smoke then before. 
 

Yeah sounds like the rings since you replaced head gasket. Leak down tester would confirm

I gather if you pull the fill cap on the valve cover, you'll get lots of oil "vapor" coming out?
 
What your describing is piston ring blow by, IE the rings are worn out-allowing combustion gases
to push into the crankcase.  
 
As long as the cylinders are not scored up, no MAJOR wear to them, you can hone the cylinders and simply re-ring the pistons / engine...  
 
My 18 HP Brigg's (from my Toro zero turn). Had to replace the piston, rings and head 
as a valve seat let loose... Cylinder was fine, just a hone for the new rings to seat..
That was 5 years ago, doesn't burn a drop of oil (nor leak):
 

Thank you gentlemen for the information.