That would work, Ed. It'd be a bit of a cut & paste party. Maybe add an "Urban Planning" tech area
with low cost, so that it's an optional complication in case not everyone wants to do it.
Note though that I would then double the cost of the Cultural Center which could be upgraded to, because upgrades are always half-price. Arcology would remain something that needs to be build from scratch, because of what it is.
PvK