I would not run one overfilled. If you look at the inside of an engine, you will see a crankshaft and an oil pan under it. It is designed for the oil to be between two specific points.
If the oil is overfilled to the point where the rotating crankshaft comes in contact with oil, the crankshaft will aerate the oil as it rotates. When oil is aerated with air the oil pump can no longer pump oil throughout the engine so the engine is starved of oil and the oil pressure falls off.
We dont have any idea how overfull your bike needs to be when this happens. It can also cause excess crankcase pressure that will damage seals. Also, at high rpms, the high oil level can cause oil to be vented into the airbox.
Again, we dont know what level this happens at, or if it will, but why chance it?
If you go up to a cold bike, it takes all of 10 seconds to remove the drain plug, let a cup of oil drain, then put it back in.
The diy stuff is awesome, but you have to do it correctly. You save the "oh, screw it" moments for when you accidentally put a piston ring in upside down, not for something that is fixable in 10 seconds.
I know this guy, well call him rcannon408, who did this to a brand new Toyota Corolla. It blew several seals and cost 2500.00 to fix. 408 had kept his oil oil, so he put that back in to not look suspicious when he took it in for warranty.
Kawasakis old zx12 would lose 10 hp, on top, if the oil level was even at the upper end of the sight glass. You had to run that bike in the middle, only.
You are trusting the bike with your life. This is a small deal, but dont ever accept shoddy, half assed repair efforts. How much oil it holds, as per the manual , is deceptive. That amount listed is usually based on a 100% dry engine. When you change the oil, not all of it comes out. Figure on subtracting 1/2 quart from the listed measurement.
Add that -1/2 qt amount of oil. Seal the bike up, then start the engine. Make sure oil light goes off. Some bikes will trap air in the new filter, and the light will stay on. . If that happens, shut the bike down. unscrew oil filter. Let the air out and start again.
Let the bike sit for 20-30 minutes, then look at sight glass. Add enough oil to get to the middle of the sight-glass.