Hello Wascamp,
Place the flywheel with the pawls facing over a slightly open vise. Using a thin punch locate the pawl pin positions and drive them out with a hammer. The trimming of the flywheel saves a little weight and requires balancing of the wheel. Use a good prop balancer or send it to a shop, such as wacker etc. The internally threaded end of the shaft can be retain to mount a spinner later. You can cut it off with a dremel or hack saw. Springs to hold the muffler are not good, but will work. It reduces your choices of after market mufflers.

Dave