knocking noise is a rod bearing.motor needs a rebuild or replaced.
find an engine here and have a local mechanic put it in,,plenty of low mileage engines.I have a similar situation. I have a 2012 Volt with 195k total miles. Of those, about 125k is ICE. Oil pump failed and the engine needs to be replaced. I'm trying to figure out what to do now. I feel my options are pretty limited and my wait in MO for a Bolt EV is end of the year. I do think it's funny the ICE is what failed while I still mostly have the same range of a new one on electric. At least I can drive it close to home!