As Andy is saying, just because dyno numbers differ, does NOT mean anybody is lying. Things are NOT exact, don't care what some care to preach. I dyno most motors, NOT in an attempt to wear it out on the dyno and have a cool sheet to show people, but for the purpose of making sure it is sealed up, the carb is right and it shows to make about the power it SHOULD, based on the parts.
I built a 632 for a guy a few years ago, it made X power on a certain dyno. The next year after a freshen, we ran it on a different dyno. It was down 80hp and he was concerned. I pointed out that it burned the SAME amount of fuel, at the same air fuel ratio on both dynos, so regardless of what the sheet says, it makes the same power it did. One was a properly calibrated Stuska, the other a properly calibrated Super Flow
So which one was correct. Only one of the HP numbers can be correct. Or, I guess both could be wrong. How would you know, other than time slips?
I get it that there are variables, and that would account for SLIGHT differences in outcomes. But to try to get me to believe that one guy loses 80 HP and that's NOT an issue...well, you won't.