Engine Serial

A compression test would tell if the engine is basically sound. You can even test that by hand by pulling on the fan belts. If you feel each cylinder strongly and they hold pressure a few seconds, it sounds good to me. "Rattles" sounds like a worn timing chain slapping, but could be valves need adjusting (more of a ticking). 1965 should have 3 core plugs, staggered. Later blocks had 5 in a row. You can find a chart with casting no.s here, but it isn't complete.

When I lived in Atlanta, people made redneck jokes about Bama people (as you probably do about MS, and so on), but I find it hard to believe the police wouldn't follow up on someone threatening a complaining customer with a firearm, especially in 1990. Your uncle should have pursued it, since the guys actions would have been very damning in court, just in the civil complaint. I never let losers off, even if it costs me time and money. I don't want them messing with the next person.