Castro, the then Communist President of Cuba, also bought 4,000 Belgian-fabricated arms from two middle-men who had strong links to the extreme German right.
It sheds light on the extent Castro, who in public was stringently committed to socialism, was willing to go in order to further his grip on the island nation and prevent an invasion from the US.
Bodo Hechelhammer, historical investigations director at German foreign intelligence agency Bundesnachrichtendienst (BND) said: "Evidently, the Cuban revolutionary army did not fear contagion from personal links to Nazism, so long as it served its objectives."
The documents, released by the BND and published online by German newspaper Die Welt, show a series of plans developed in October 1962, at the height of the Cuban Missile Crisis.
They reveal that two of the four former Nazi SS officers invited to La Havana had taken up the offer, and that they would receive 'substantial wages' of more than four times the average German salary at that time, the New York Daily News reported.
And regarding the purchase of right-wing linked arms, they show how Castro, now 86, had dealt with two traffickers, Otto Ernst Remer and Ernst Wilhelm Springer, in buying 4,000 pistols.
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The conclusion drawn by German secret service officials was that the Cuban regime wanted to lessen its dependence on buying Soviet-produced arms.
October 1962 was the month that the US and the USSR came close to going to war over Russian missiles stationed on the Caribbean island.
The 13-day confrontation, between October 16 and 28, ended when a secret deal was reached between US President John F Kennedy and Soviet Premier Nikita Khrushchev.
Publicly, the Soviets agreed to dismantle the weapons in Cuba and return them to the Soviet Union, subject to United Nations verification.
In turn, the US agreed to declare that it would never invade Cuba. Secretly, the US also agreed it would dismantle all US-built Jupiter IRBMs deployed in Turkey and Italy.