I also have a 1968 Mustang 289 with 70,000 original miles which works out about the same miles/year as this one and the car runs great, I've never had a problem (however I use a mixture of unleaded and 112 octane race gas)
Yes, over the years I've replace most of the rubber proactively, except for the spare which is original and only for show.

The car was purchased as a carrot (and investment) for my daughters education when she started high school. She was driving it about 3 block to school on occasion but wasn't impressed with the 8 mpg.

Ironically she'd come home and get Bert or Ernie, her and her sisters 240s. What's more a lot of her friends have asked me to find them 240s too. Over the years I think I found a half dozen or so all under 100k which friends and family (or I) have bought.

So beauty is in the eye of the beholder and while I think 10 grand is too steep, I would love to get my hands on a very low miles 240. I called the guy and I'm going over to look at it tomorrow.