Need some information about Mantinea 207 BCE

[Paullus Scipio]

My sources put him closer to the beginning than the middle of the century, thus closer to the origination and surely within the first wave of inventors

Presumably these are secondary sources, of whom Kingsley seeks to push Zopyrus closer to the first batch of artificers, but there is no evidence for this in the primary sources.
"The traditional dating for Zopyrus puts him in the first half of the fourth century, but Kingsley has argued that he was in fact active in the last quarter of the fifth century, when he designed artillery for Cumae and Miletus (1995, 150 ff.). In a famous passage, Diodorus reports that in 399 BC Dionysius I, the tyrant of Syracuse, gathered together skilled craftsmen from Italy, Greece and Carthage in order to construct artillery for his war with the Carthaginians (XIV 41.3). It seems not unlikely that Zopyrus was one of those who came from Italy."

The problem with this is that Zopyrus' machines, as described by Biton, are clearly later developments of the original gastraphetes type, which fits a date c. 350 B.C. much better than placing him earlier with Dionysius' original inventors. There is no real reason to 'push' Zopyrus' dates back, and plenty of reasons not to.