I question whether the original death here would have been tracked as rabies Vs heart attack.

Which also suggests perhaps it is slightly more common than data suggests

From the CDC report [1], it's pretty clear that rabies was not considered for the donor until after the donee died and rabies was confirmed. Possibly because the donor had been scratched by a skunk and not biten. The report says the scratch had been noted on the donor risk assessment interview (DRAI), but that skunks are not considered a reservoir for rabies in his area.

[1] https://www.cdc.gov/mmwr/volumes/74/wr/mm7439a1.htm

Skunks also aren't aggressive...

I thought rabies had to be considered for any interaction with a wild animal. For one showing atypical behavior, the indication is that much stronger.

Theoretically, the donor could die before the rabies infection developed into a disease. For example, in a car crash. IDK if this was ever the case. The incubation period is definitely long enough for this to be a plausible scenario.

Going by wikipedia, the incubation period can be up to three months. That isn't a particularly significant span of time if we're measuring how likely someone is to suffer an unexpected death. It's long enough that the possibility exists, but that's about all you can say.

Assuming an even distribution of deaths: 3 months / 80 years = 0.3% But there is very little people that is incubating rabies.

But the question isn't "what are the odds someone who dies in this period has rabies" it's "what are the odds someone who died after being infected with rabies died before they started showing symptoms" so the rarity of people incubating rabies is irrelevant.

Further, rabies incubation is highly variable - symptoms may not appear for years.

nit: surely the bounds for an acceptable organ is < 80 years old and > 15? maybe the window is closer to 50 years?