My recommendation is if your are not gonna use the 29 G for a fish in specific use that tank to raise the Fry's. You have many Cichlid that you can house with the Con that will end up eating the Convict Fry. And will be OK on the 66 Gal with the con the only problem is that there will be lot of aggression, since they are a breeding pair.
Let me know what you will be doing.
O69