I've purchases a rebuilt K04 with a new CHRA installed by SoCal porting. They also polished and ceramic coated the headers. Might we worth a shot letting them check it out and rebuild it for an easier sale.
I don't think it's dumb to K04 at 80k+ miles. I don't have that many miles but I know a few forum members have done it. Just make sure your engine is healthy and doesn't have too much carbon buildup.