Hi @nishav
I use Factory Limited from the Redesign Thread. I find them to work well.
“FactoryLimited” Air and Naval Bases now cost 12. All captured and newly constructed Minor Factories may only produce Artillery, AAguns, Armor, Mech Infantry, Mobile Infantry, Marines, Elite and Infantry. If a NB is present you may also build Subs, Transports, Escort Carriers and Destroyers. If an AB is present you may also build Fighters and Tac Bombers.ABs are required to build Fighters, Tac Bombers, Bombers and Air Transports. Bombers and Air Transports may only be built in Factories on originally owned Territories that also have an AB. In addition, Bombers and Air Transports may not be built in the following territories: Kwangtung, Egypt, Norway, Alaska, West India and Korea. May not build at an AB with 3 or more damage.
NBs are required to build all Naval Units. BBs, CVs and CAs may only be built in Territories with originally owned starting Factories. These Territories must also have a NB (Need not be original NB). May not build at a NB with 3 or more damage.
So similar to what you’ve suggested. Basically the Big Guns can only be built in original major factories.