OK, here's what we found: The darn limitter cap was left off the carb after the previous owner messed with it. This allowed the previous owner to come up with a bad fuel/air mix and, most likely, a run speed that was too hot for the piston and cylinder to handle. They're both badly damaged. I never touched the carb adjusters.
Parts, alone, are $400 plus about two hours of labor. So, I can pop for $600 and get a used saw that should be good to go, or I can spend another $250 and buy a second new 460. I'm going to think it over. Again, damn eBay! I should have spent an extra $39 to have the Stihl service center, here, check the saw out before I ever fired it up.
Save the put-downs, please. The saw ran well, as far as I knew, and it did a very good job for a good, long while without showing any signs of wear or tear. While I'm fairly certain that some of you saw guys might have sensed that something was out of adjustment right off the bat, I had no basis of comparison, except to my 440, and I knew that the 460 was supposed to be punchier. I'll be more careful now, you may rest assured.
Thanks to those who gave me good advice. I honestly do appreciate it.
Happy Thanksgiving to those who celebrate it. Enjoy your days off!
-Miles