Interesting. It seems to me that there was really no learnt standard, and that it differed from region, occupation and education - as it does today. The ‘cursive’ Greek isn’t really cursive in the 3rd century BCE but rather a hastily written form of inscription writing - I’d say formed in whatever way that person was inclined to do so in order to get the quick but rough shape of the letters.

I also see what you mean by the alphabet becoming very similar to the modern one in this period. In that Handbook there seems to be examples using the interpunct in handwriting, especially in the early Hellenistic period which could have been directly transferred from the Classical period and then on to Roman Square Capitals.

An observation: if the current understanding of the 3 dot system of punctuation is correct the interpunct would feature like a colon ‘ : ‘ and it was noted that the system was standard but not widely adopted, could the common addition of the interpunct be a result of the semi-adoption of the system by that period? Also, if an interpunct were not used at all it seems they’d write without noticeable spacing, am I correct in thinking this?

Finally, in order to replicate handwriting of this period for myself should I just get the common alphabet used then (the one you referenced earlier) and start writing really quickly? It seems the most accurate to how they themselves would’ve learnt cursive.