Don

If all the oil was coming from the manifold surface there would be a trail around the valve stem/guide area---that looks like the oil came directly out the guide

Before I would go to all the work of a different block, I would see what/how much size it takes to clean up that area----sometimes a little detonation will knock off the ring land of the piston and they scrape like that--you can probably see pass the top edge and get an idea of what happened--rock the piston over a little with a screwdriver blade for a better look