I think I know the root of the problem.

Sekonic L-758C reads directly in foot candles (Incident with dome retracted, Advanced function 16 setting 2)

Weston Master scale is labeled with brightness units in a series similar to foot candles but I believe it is an arbitrary scale about 4 stops higher.

My Sekonic L-28C is a true incident meter with a scale that claims "foot candles" on the faceplate. Setting ASA 64, rotate dial L indicator to 64, the computer recommends f/8 between 1/2 and 1/4 second.

But on a Weston Master if you try to dial in the same number (for example 50 which is close to 64) you get a recommended combination of f/stop and shutter speed that is four-stops higher. For example setting Exposure Index 64, rotate arrow to 50, computer recommends f/8 at 1/50.

Ansel Adam's Exposure Formula is not valid for real foot candles. It is valid for the old Weston Master meter brightness units instead.

p.s. SEI has a scale for Log Foot Lamberts