:welcome: Again,
Please do not post the same problem multiple times or in multiple sub sections of the forum it gets every one confused.
Go to the briggs & strattone web site, click on support then manuals .
enter your engine model & code numbers then download the parts book.
Anything or everything inside the crankcase could be damaged beyond repair and without pulling it down it is pure guesswork.
In most cases the engines are not worth repairing as you can get a superceeded / surplus engine for not much more than the cost of parts to repair yours and the engine comes with a warrantee.
You are going to have to pull the engine out in any case so sorry, you may as well start on that right now.
Pull the blower cover and flywheel off with the engine in the mower , it is a lot easier to do that way.
next pull the pulley off, then disconnect all of the wires, undo the 4 bolts holding the engine in and out it comes
Replacement engines come complete ready to drop in usually the only parts you need off the old engine will be the muffler & pulley.
If you bought one with a smaller alternator than yours you can swap out your stator & flywheel is necessary.
This one is $ 399 + shipping and will drop right in with only your muffler needing swapping
https://www.smallenginesuppliers.com/shop/html/pages/products/briggs_vertical_shaft_engines4349.html
Then put your old engine on evilbay and you will probably get $ 100 for it as a single lump or $ 200 if you want to part it out
Now to stop yourself doing the same thing again, go to a hardwear store or locksmiths and buy a very large keyring, around 2" to 3" is good.
Put your mower key on it and hang it over the dip stick tube. Leave your keys there when ever you are not mowing thus the keys will not get lost & you might remember to check the oil every time you mow.
When I service a mower, I remove the dipstick and leave it on the seat till the oil is replaced.
No oil, no dipstick. If it is going to be a long while before I refill the engine then the filler hole gets a sink plug or shop rag stuffed in there but that dip stick never goes back until the oil is in the engine.
It is a very easy and very costly mistake to make.