I've never heard of any one measuring either, the only reference to candlepower I've seen was on the Dietz #40 and rather than a number it simply said "pencil beam". The light output would depend on the type and color of the globe used along with the angle it is viewed from. Since most were fitted with the Fresnel type lens which amplified and concentrated the light into a beam I imagine candlepower wasn't much of an issue as long as the flame was properly adjusted nor would the BTU rating. Many railroad switch lamps and other markers used the 1/4" round wick with Fresnel lenses and were visible from considerable distances which was the real issue regardless of the seemingly faint output of the flame. Maybe one of our more scientific minded contributors might know more.
Willis