It's a little hard to advise over the net, but leave the final cleaning up of the flywheel till later.

You could possibly hacksaw off the tops of the steel pins to remove the starter pawls, but leave the rest of the pins, and if I'm making a prop hub for you, I can mill or turn them down flush and tap some bolt holes into them to hold the prop hub.

Careful handling the flywheel, - don't bang it around too much, as the magnets could lose their touch.

Carefully remove the fuel tank from the the crankcase, with a hacksaw etc. ( a grinder would take forever) being careful not to cut into the crankcase! also always think deeply before cutting any lugs off. ( these can be very useful sometimes).
I'll have a good look at the photos later, and perhaps examine the engine I have, (if its the same), and I'll be better able to advise you.

Not yet sure if it's a ball or needle roller crank, ( may need to see inside yet!) I think they might be needles, - one easy way to check is to push and pull the shaft and see if you get end play, if it has, it will be needles, and if it doesn't, it'll be ball.
If it has needles then I would have to make up some sort of thrust bearing for you.
- all this of course is if you'd want me to do it!
Don't worry, I won't charge anything like jobbing shop rates!
Keep in touch.