Using the Nukemap simulator a 500kt device on Gragemouth will destroy Falkirk, however Stirling is beyond the main effects of the device. You have to go up beyond 3 MT before even just the thermal effects of the initiation reach Stirling. A weapon in the 500kt to 1MT range is most likely.
Interestingly a weapon on Grangemouth also gets you the power stations at Longannet and Kincardine, plus the Kincardine Bridge.
There are likely to be three GZs in that part of Scotland - Grangemouth/Kincardine, Rosyth dockyard/HMNB Dockyard and MHQ Pitreavie and that's ignoring the weapons on Edinburgh.
However I don't think that it was ever decided whether Grangemouth was directly targeted during the nuclear exchange, though it was probably attacked during the conventional phase.
Interestingly a weapon on Grangemouth also gets you the power stations at Longannet and Kincardine, plus the Kincardine Bridge.
There are likely to be three GZs in that part of Scotland - Grangemouth/Kincardine, Rosyth dockyard/HMNB Dockyard and MHQ Pitreavie and that's ignoring the weapons on Edinburgh.
However I don't think that it was ever decided whether Grangemouth was directly targeted during the nuclear exchange, though it was probably attacked during the conventional phase.
