Ah.Thing is, what if the politicos intervened to stop the chemicals from being used?
Just because the military wants to do something doesn't mean it will get done if the politicians get involved.
Or what if one side or the other calls for a halt after the initial nuclear and chemical use, knowing well what it could lead to?
Soviet doctrine - about as sensibly as one can imagine - prioritized nuclear delivery systems for targets of their conventional forces in so-called conventional phase of war, making the situation "use it or lose it" for NATO. In similar way, priority target for USN were the Soviet SSBN's.
Additionally, it would be very difficult to execute such a limited nuclear fire plan in which enemy C&C would be left sufficient to prevent spasm use due to distrupted communications etc. Nuclear weapons were too central to cold war military mindset simply to be ignored in Clancyesque style.
The another question of course is if the nuclear war would have been winnable in 1970's to 1980's timeframe for the US, in sense that the USA would have been the last man standing. It's possible, I think, due to much better condition of US strategic forces compared to their Soviet counterparts.
Personally I think, if one would want to develop a realistic WW III scenario for late cold war it would involve first use of nuclear weapons by WP from the outset of the war. With first strike in a bolt out of blue, or virtually bolt out of blue, scenario most of the NATO tactical and operational nukes could have been eliminated along with the best NATO conventional forces. Conventional weapons could be spared to destroy nuclear bases in UK in order to prevent UK independent nuclear deterrent from working. Most of the remaining NATO tactical nuclear weapons and operational nukes would be fired upon Eastern Europe. European NATO countries would be presented with an ultimatum over ultimate destruction or surrender.
Then the US would have been left essentially with option of fighting an intercontinental war with USSR, in which it would fairly surely suffer from massive damage, or enter negotiations with USSR about new security arrangements. The US leadership would be faced with question whether to sacrifice USA over already damaged Western Europe. This scenario is a very long shot.