If it's still in the bus change the fuel lines. Regardless of where it is remove the tin over the cylinders and clean out the mouse nests, also retrieve the spare spark plugs and plug socket sitting ontop of cyl #3
. Put a spoonfull of oil into each cylinder and prime the oil system through the sender hole with a small funnel.
If you are happy with the way it runs you'll want to change the front and rear crank seals, the pushrod seals, the gasket under the oil filter adaptor and the O ring on the oil pump. Peening around the oil gallery plugs is a good idea too.