You have to understand that ancient feet were derived from stadiums and not the other way around. Thus one could divide a stadium into 500 units and come up with one foot measure and the other divide it with 600 and come up with another foot measure. Also there were different stadium lengths at different times that related to the dimensions of different celestial bodies.

Regarding the 328 mm version. We have:

328 mm x 500 = 164 m

According to Dimitris Tsimpourakis “Mathemetical Measurement in ancient Hellas” the length of the common Hellenic foot was 328 mm – the stadium length being 164 m. If I am not mistaken this was used during the Hellenistic period. We can refine this more taking into account Stieglitz’ value0.3275 meters which agrees better with the astronomic data(163.75 m stadium).

From the same book we read that the Attican stadium (4th century BC) had a length equal to 165.39 meters, thus since it consisted of 500 feet, each Attican foot had a length equal to 330.78 mm.

I really don’t know if a foot measure with a length of 0.3552 m was in use at ancient times. I also doubt the 297 mm foot measure was a new measure invented by the Romans. In Athanasios Aggelopoulos book Metron Ariston he sites the Roman foot as having a length equal to 0.273 meters a length almost identical to the 0.27432 Assyrian foot. On the other hand in the same book the Hellenic foot is given to range from 0.297 to 0.3083 meters. If we multiply 297 mm by 600 we get:

297 mm x 600 = 178.2 m

The Delphic stadium length is 177.55 meters , but it’s possible that the 178.2 meters length coincides with the Nemea stadium length which cannot be measured with good accuracy(it is given to be 177 to 178 meters). In this case we would just have to divide it by 500 and get the 0.3552 m value.