First off, this forum would probably been a better place for this as this isn't a world specific issue.
* As far as the question itself, it depends on how extreme you want to go. Do you want the ability to conquer another city with this manti city? If so you'll need a 20+ harbor and 22+ academy to be able to build a colony ship.
* Secondly, do you want to build a pure manti nuke or will you consider a mixed nuke? A pure manti nuke is of course stronger, but mantis take a long time to build thanks to their favor requirement, and you may want to build a mini hopolite nuke or the like with the spare space to attack with in the meantime. Also, remember that while you don't need a navy with air units, if you're doing a mixed nuke with land/sending a cs to always use light ships.
* Thirdly, is your city at any risk of being attacked? If so you might want a level 25 wall and a tower. If you are safe, you may want to save the population for a larger manti nuke. Also consider that you may be bolted and quaked and need to rebuild a building.
And here's an example build for a pure nuke build maximizing space for more mantis over everything:
senate: 10 (the lower it is, the longer the rebuild times)
resources: 5 (mantis are favor constrained, not resource; and if you need resources send it from another city)
warehouse: 30 (lower if you want/less points=more morale)
barracks: 5 (mantis are favor constrained, not build time constrained)
temple: 15+ (higher temple=quicker mantis, but it has diminishing returns/lower temple=more mantis
academy: tear it down as much as you can
wall: 0/25 (depends on if you need to defend)
tower (defense)/divine statue (extra favor)/nothing (extra space)
(this exact build probably isn't going to give you a population divisible by 45, which means you should have some extra space to build up a few buildings of your choosing)
And the academy for the pure nuke:
Meteorology, Plow, Colony Ship (isn't needed but it doesn't cost any points), Conquest (so you can revolt with the mantis)
And if you need defense: City guard, Battering Ram, Phalanx
notes: as far as I know Phalanx doesn't work on myths so you don't need it for offense with pure mantis, and other reseach isn't really needed and limits how far you can demolish the academy
Whether you'd really want this build, or if you'd want something different depends on what exactly you want to get out of the city.
thank you this is exactly what I was looking for currently I am pushing 63 manti's in my citi but the build is all over the place and yes the pure nuke is what I want I have been looking through the forums and seen numbers quoted of 70 & 71 but never the citi build with it so this will be very helpful I will be checking out the other forum you suggested