Given that these figures are not naturally proportioned, but are proportioned along the usual 28m "heroic" lines, I think it's a bit irrelevant whether they measure up exactly to 1/56 scale vehicles (most 28mm figures are oversize, which is why many players prefer 1/48 scale vehicles). I think it's more important that they look good next to the most commonly used 28mm figures, even if they're slightly different looking.