You can buy KM4680 on ebay - there's a bunch of NOS for sale right now on it - typically a few appear, get bought out, then get re-stocked a month or two later
I changed my hoses last year and then my coolant crossover corroded and rusted through, grrrr, so I ended up just replacing it all with Cobra Engineering's cross-over delete. I wish I'd done that from the get-go