I once saw a list of many of the common small engines at an industrial engine dealer. It had a number by each model for the "expected" life for those engines on the list, when used for HD work.
The Honda OHV was number two on the list and the expected hours was 2500...
The top of the list was a Kubota diesel at 4,000 hrs
Common cheapo motors like the flat head Briggs IC was 300 hrs.
The Kohler flat head was something like 1000 hrs. or 1500 I forget for sure.
As a side note, I was running a couple B&S IC powered 2" water pumps back then, and I kept meticulous records on them, changing the oil every 10 hours as was specified in the owners manual. By the time each one hit 300 hours, they started hard and were waaay down on power!
I finally gave up on those cheapo motors, and bought a gas powered Kubota pump, NOW that pump was/is MILES better than any other pump I had used at that time. I still have the Kubota pump and it's still working just fine, I wish I knew how many hours that gas powered Kubota motor has on it.
SR