I looked into the over(under?)size bearing option but the nearest I can find to a 6308 (ID 40mm) is a 6406 which has an ID of 35mm. I assumed that would be too much "meat" to take off the crank journal?? Certainly the cheapest option - if I can find someone who can split the crank to remove the rod.
Been given names of a couple of places that might be able to help with re-engineering (journal spray welding & grinding or journal grinding and sleeving).
But given the amazing condition of the rest of the engine/gearbox I'm in two minds as to whether to risk a possible bad fix that might cause more extreme damage.....???