Thanks to Daniel for a fine analysis. I looked at 22/13 and 13/9 13/8 here and didn't seriously consider 6/2 6/1. Eventually I played 22/13, underestimating the gammon danger.
Note that 13/9 13/8 isn't too far back.
|  1. | Rollout1 | 6/2 6/1 | eq: -0.672 | 
 | Player: Opponent: |  21.72% (G:3.51% B:0.08%)  78.28% (G:21.22% B:0.88%) | Conf: ± 0.009 (-0.681...-0.663) Duration: 1 hour 56 minutes |  
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|  2. | Rollout1 | 13/9 13/8 | eq: -0.698 (-0.026) | 
 | Player: Opponent: |  20.77% (G:2.89% B:0.10%)  79.23% (G:20.93% B:0.91%) | Conf: ± 0.009 (-0.707...-0.689) Duration: 2 hours 14 minutes |  
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|  3. | Rollout1 | 8/4 8/3 | eq: -0.724 (-0.053) | 
 | Player: Opponent: |  21.95% (G:3.47% B:0.08%)  78.05% (G:26.90% B:1.29%) | Conf: ± 0.011 (-0.735...-0.713) Duration: 2 hours 00 minute |  
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|  4. | Rollout1 | 22/13 | eq: -0.734 (-0.062) | 
 | Player: Opponent: |  24.94% (G:6.74% B:0.32%)  75.06% (G:38.27% B:1.27%) | Conf: ± 0.012 (-0.746...-0.722) Duration: 1 hour 50 minutes |  
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|  5. | Rollout1 | 13/4 | eq: -0.748 (-0.077) | 
 | Player: Opponent: |  19.70% (G:2.83% B:0.08%)  80.30% (G:23.68% B:1.00%) | Conf: ± 0.009 (-0.757...-0.739) Duration: 1 hour 59 minutes |  
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|  6. | Rollout1 | 8/4 6/1 | eq: -0.766 (-0.095) | 
 | Player: Opponent: |  20.71% (G:3.17% B:0.06%)  79.29% (G:27.79% B:1.15%) | Conf: ± 0.010 (-0.776...-0.756) Duration: 2 hours 57 minutes |  
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1 1296 Games rolled with Variance Reduction.  Dice Seed: 2  Moves and cube decisions: 3 ply
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