All throughout High School, (1978-1982) I flogged a very early hipo Mustang that still had its original engine. Never touched the carb, but it had, easy 150,000 miles on it. And I surely didn't care for it, beyond
oil changes. I literally broke the gear shifter OFF the four speed (w/lockout) transmission. (I always thought it was a toploader, though I've been told recently it may have been a T10.)
These Ford engines were built real stout. Out of the 6 Mustangs I've owned, only one was a sub-100k engine, and it was a 6, which I've recently replaced with a roller motor.