I don't think there is that many data points missing. My best guess is 1-2, so 2 at the most. The problem, of course, is the altimeter is not correct because it's not calibrated for those speeds and pressures.
If you have a way of quantifying the altimeter error given the airspeed, I'd love to see it. From my initial research on the issue, I thought that question was a non-starter.