Hi Al.
You raise a difficult question. Assume a primary tactical unit of
256 men wasn´t even appropriate for this era. But your idea of breaking the Phalanx structure down to more flexibel units of
4 x 64 men might be historically accurate.
After the Marian reform, the Roman Legion consisted of 10 Cohorts, with 6 Centuries of 80 men each + 5 overstrength centuries of 160 men. The primary tactical units were the centuries.
This structure undoubtely resulted from a developement of army organisation, means your model might be a missing link.
In my opinion the dominating element in Alexanders strategy was the Phalanx tactic and the crack elite Macedonian Cavalry.
Others units were used for support. But Hannibal used even his skirmishers or the Numidian Cavalry as an independent tactical element.
Cheers, Klaus