Najdorf 6.Be2

Before tackling the main question in Unzicker - Fischer, 1962 Varna, I decided to address Kasparov's notes on the opening. He first commented on the sequence 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Be2 e5 7.Nb3 (diagram) in his notes to the game Geller - Fischer, 1962 Curacao (2nd round), Predecessors II (p.308).

After 7.Nd4-b3

On 6.Be2, he quoted Mednis,

A deceptively quiet continuation, introduced by Smyslov and worked into a powerful weapon by Geller. White simply continues his development and is neutral about the Najdorf: neither trying to refute it nor being afraid.

I've also adopted the move when meeting the Najdorf. The games are generally fluid and don't result in the same sort of computer friendly tactics seen in other Najdorf continuations like 6.Bg5 and 6.Be3. Here are Kasparov's notes, abridged where I've used square brackets '[]'.

Geller - Fischer, 1962 Curacao: 7...Be7 ('The most accurate move order. The alternative of those years was 7...Be6 [...]') 8.O-O O-O ('Again the most accurate, although 8...Be6 9.f4 Qc7 is also played, not fearing 10.a4 [as in three games from the Karpov - Polugaevsky 1974 match; Kasparov gives three more alternatives to White's 10th from his own games]') 9.Be3 ('Currently the subtle 9.Kh1 is also in vogue, while Geller at the end of his career tried 9.Re1 with the idea of 9...Be6 10.Bf1 [...]') 9...Qc7?! ('The first steps in the theory of this variation: without f2-f4 having been played yet it is rather too early to determine the position of the Queen! 9...Be6 is correct, for example 10.a4 [...]. Later both Geller and his protege Karpov adopted 10.Qd2 [...]. 10.Nd5!? Nbd7 11.Qd3 Bxd5 12.exd5 gradually became the modern tabiya.' 10.a4.

The Curacao Candidates tournament preceded the Varna Olympiad.

Unzicker - Fischer, 1962 Varna: 7...Be6 ('Later it was established that 7...Be7! is more accurate. This, in particular, is what Fischer played against Geller in Stockholm and on Curacao.') 8.O-O ('The slightly premature Bishop sortie to e6 can be called into question by the energetic 8.f4 Qc7 9.g4') 8...Nbd7 9.f4 Qc7 10.f5 'The main plan at that time. By the mid-1970s White had switched to} 10.a4 Be7 11.Kh1!? (one of Geller's many ideas) -- this is a tabiya of the 1974 Candidates match Karpov - Polugaevsky.') 10...Bc4 11.a4 Be7 11...Rc8? [...] Black should keep his Rook on a8, so that after the typical ...b5 and the en passant capture a5xb6, the a6-Pawn is not hanging.') 12.Be3 ('In the following decade 12.Bg5 O-O appeared [...]') 12...O-O 13.a5 b5 14.axb6 Nxb6 ('A tabiya of 1962 -- and the entire decade! Bobby upheld it against both Tal and Geller on Curacao.')

Kasparov also covered the variation in Predecessors V (p.232), when he discussed the 1974 Karpov - Polugaevsky match.