You can take your flywheel to a machine shop, they can repair it for you. Timing chains and gears, replace them. Magneto used, yes but test it. As for all your bearings, there are clearances to check, if they meet the minimum, your good. Look for any gouges, or obvious signs of stress. If you have the money, you can actually buy a short block for just under $800, that will come with most of the problems, solved.