Thinking a lot about valves lately

A few days ago on F-chat, I was reading about the woes of a fellow 308 owner. Seems he just got his car out of the paint shop and was driving it around happily. All of a sudden, he heard a crunching noise coming the engine bay and the car stopped. After having it towed to a shop, he found out some really bad news. The engine dropped a valve and the engine was trashed.

In the early 2 valve 308s, Ferrari used sodium filled exhaust valves. The thinking here was that a sodium filled valve stem provides better cooling than a solid valve stem. On the exhaust side, this supposedly helped in drawing heat away from the valve head. Unfortunately, this also meant having a weaker valve. The stem had to be hollow so it could be filled with sodium and the valve head was welded onto the stem. Many people consider these valves to be time bombs -- the valve head could separate from the stem at any point and destroy the engine.

A lot of 308s have had head work done by now and had these time bomb valves replaced with solid stainless steel valves. What about my car? Since I don't know the service history, I have no idea if the valves have been replaced or not. I can tell that the clutch has been replaced before, but I can't tell if the heads have ever been off. I do have the contact information for the guy who has worked on this car in the past. When I get a chance, I'll call him to see if he remembers my car. Hopefully, I can get confirmation on whether my valves have been replaced or not. In the meantime, I don't know how much I should sweat the fact that my engine could destroy itself at any point.