Frankly I find the idea that outside the core allies of both blocs, the rest of the world is being unmolested, to be hard to swallow by the 70s, and ludicrous by the 80s.
If you're firing 20,000 nukes at each other, you're going to reserve a portion, even if it's just a couple of percent for taking your opponents secondary allies and sympathesizers, as well as overseas assets (such as industrial plants), and forces deployed overseas. Additionally, nuclear war will be fought on the high seas, and ports which provide a haven to enemy ships or trade may be nuked. And this quite aside from a motive that post-war you don't want some neutral neighbour to move into your territory (something I am sure the USSR would consider).
As far as the USSR is concerned:
Apart from NATO, A/NZ, Japan, China, other probable targets in all out exchange would presumably include at least some of:
AMERICAS:
- Most countries in the Americas are at least nominally US allies, esp. Mexico, Brazil, Argentina & Columbia
- Panama Canal is an obvious target
- Oil targets in Venezuela
AFRICA:
- Egypt is US ally after 1973
- Ethiopia is a US ally prior to the revolution
- S.Africa is an enemy (Rhodesia too until 1979)
- Nigeria home to BP assets
- Kenya - British base
- French forces scattered around Africa in various countries
- Portuguese colonies in Africa prior to 1975
MIDDLE EAST
- Israel
- Iran (prior to 1979) is enemy, and contains US assets. Even after 1979, I think the Soviets would prefer not to leave an undamaged Iranian regime on their border if their own country is wrecked.
- Saudi, Bahrain, Qatar, Kuwait, UAE - Western oil assets. Saudi also has US AWACs after 1979.
- Oman = British ally
- Cyprus - neutral, but British bases
SE ASIA & OCEANIA
- S. Vietnam (prior to 1975)
- S. Korea
- Taiwan
- Philippines (US ally)
- Malaysia (British ally)
- Singapore
- Pakistan, inc. E.Pakistan (prior to formation of Bangladesh) - US ally
EUROPE:
- Sweden, Austria, Ireland & Switzerland - all neutrals, but surely perceived by the USSR as ultimately in the Western camp.
OTHER:
Scattered US & British & French bases around the world, like Falklands (Mount Pleasant), Ascension, Diego Garcia, various US bases in Pacific, French Pacific nuclear test site, etc.
As far as the US is concerned:
Other probable targets in addition to USSR, Mongolia + Warsaw Pact, in all out exchange would presumably include at least some of -- in most cases because they are Soviet allies, and contain significant numbers of Soviet/WP/other-communist troops, bases or advisors
Cuba
Angola (after 1975)
Mozambique (after 1975)
Ethiopia (after revolution)
Other countries in Africa with Soviet bases
Egypt (prior to 1973)
Syria
Iraq
Libya
possibly Algeria
N.Korea
Vietnam (or N.Vietnam prior to 1975)
Yemen
Afghanistan (after 1979)
possibly India (has an alliance with USSR)