Hi Chris, I would walk away or get a discount of £15k, in my view it will be difficult to get insurance if proper documented remedial work isn't done. We recently had water ingress and thankfully it wasn't the keel but I did go through the budgeting aspect of removal and including lift out and surveyor report it was at £12k with a proviso that it could go higher if further investigation found unforeseen work. If the boat is out of the water ask the vendor to have the gel coat stripped back about 8” or so all around the keel hull joint and get the surveyor to inspect the fibreglass underside in case the cracks have gone right through. There should also be hull deflection if a grounding has not been light for example outward deflection at the front and inward deflection at the rear of the keel. Good luck.