Regarding the "gash", I have a story for you. A farmer had a White tractor that broke a ring. This then wore vertically into the cylinder wall. I do not know who put rings in it, but the engine had a misfire or popping noise. On a NA diesel you can remove the exhaust and intake manifolds and listen at each port. If you remove the wire off the fuel solenoid, it will not start. You crank it over and can hear a leaking valve. When he did the rings he had a machine shop about an hour away, touch up the valves and seats. Seems they were off on one and it leaked. I took the heads off and took them down to them to check over. Their story was the wear in the cylinder. Two weeks later they called to get the heads. Said they found nothing wrong and the problem was the cylinder wall. So I installed the heads and still the popping out the same intake. Pulled the heads and took them to the Ford dealer in town as they have valve grinding equipement. They went through them and said ond seat was off a bit which they touched up. Put the tractor back together and it ran like a top. By then I think the rings and cylinder wall had conformed and it did not even burn oil. Kind of stopped using that machine shop after that.