There was a poll taken a while back you may want to search for. I think (someone correct me if I am wrong) that the failure rate is only about 10%. The best thing you can do is keep your cooling system in good shape. This includes upgrading the fan clutch if it hasn't been replaced. Look for a blue hub on it. If your cooling system is working properly, don't worry about it and enjoy the ride.
well, I am currently in the process of replacing my headgasket. when I bought my cruiser 3 years ago I had the entire cooling system gone through-new radiator, new fan clutch, new thermostat...
it was new to me at 129k miles now at 173k, my headgastket blew.
someone wrote on another headgasket thread that all headgaskets are actively failing, I would agree with that statement.
and no, my cruiser never overheated during my ownership or prior to it blowing the hg.
I think if everyone did that mod, or had a Scangauge, Dan would sell a new radiator and fan clutch to everyone with an 80 series. My truck ran cool after the mod until I loaded it for a week long trip and cranked up the hill to Tahoe at 75 mph. I realized it was not cooling that well in those extreme conditions. It now has a new radiator and fan clutch.
The other thing to consider, is just doing a radiator replacement at 100k with the fan clutch, and then don't worry about it.