All those who ask about the circumstances and validity of old professional marks should treat those marks with a strong air of skepticism. Consider the differences of trying to set a World Record in the long jump which would be accepted by the IAAF, and trying to set a "World Record" which would be accepted by the Guiness Book of World Records.
You can imagine that the level of officiating for a Guiness record could be substantially more lax, that the runway ground may not be level, that the pit may be low, that the mark might be measured from take-off, that the mark might be measured from the take-off heel or measured to the landing toe (!), that the athlete might use weights. All of these are possible, and some combination are/were likely.