-) For this issue it does not matter whther a anolog or digital lightmeter is used.
-) From those photos the contrast between objects can be established.
-) If you know the the process from film to these images, then
-) by metering the flash exposure at same or new setting the right flash/object can be established to yield same obects cntrast.
However, I would skip the first stages, but just spot-meter on location. That would bring you close to the above anyway, if you know about the response of that film.
One could even approach the matter just mathematically by appying the flash guide-number (corrected for outdoors) and by taking into account natural light fall-off by sqare of distance (a distance which of course must known ore metered).