Thanks. The thread chaser idea is brilliant!

I went over the surfaces fairly lightly already, but head gasket remains can still be seen. What kind of disc isn't abrasive? Should I be removing all old head gasket stuff? After some work on the top of the block, a number 2 could be made out in between the cylinders. That made me think I was on the right track.

I'll look into the oil pan too, but isn't that some work with the axle right there? I guess I should do as suggested with this much time invested, but I wanted to make sure the engine ran prior to ANOTHER undertaking Patience, I guess.

Thank you for your advice; I need it. I've only dealt with German cars prior.