[Tiara Coronet] Engine overheat, impeller replaced, impeller blades disintegrated, where did they go?

[Sans Peur]

The impeller blades are blocking flow. Thats why it is running hotter. Start looking down stream from the impeller pump. Most of them are probably in the first cooler (oil, trans,,) Some may have gone further so it would be good to keep going until you dont find anything.
Don't know if yours is fresh or raw water cooled. If fresh (has antifreeze) then they are probably in the heat exchanger. Its usually on the top front of the engine. Go there first.