best option
I think that banking the eight and going four rails behind the 9 is the best plan. I would try to get the eight on the long rail as the 4 does not prevent the opponent from going up table on his next shot, but cue ball control is paramount in this situation, so just hope that it turns out that way. I would also plan on the cue ball going above the 9 on the way to the 6/7. If the 4 were not there, then this would be an even better shot as the eight would have a chance of preventing the bank combo of the 6/7 pair. Plus, this is the only shot that accomplishes more than one thing.
The other options I have seen seem to have problems:
1.Following the 5. This is a VERY difficult shot in my mind because of the short distance between the balls. They are not touching, and a double hit costs a ball.
2.Kicking behind the 6/7 (one rail). That corner pocket looks like an open invitation for whitey. Trying to kick lower with inside would prevent this, but you have to hit that shot firmer which may cause the cue ball to come back out of the trap.
3.Kicking behind the 6/7 (four rails). If you have that kind of speed control, then it might not be a bad shot, but this type of shot is mainly for when those balls are much closer to the opponents pocket. Regardless of how you kick at this, if you do not get far enough behind these balls, then you sell out a free bank on the 5, unless you come off the eight to produce a position that takes makes the opponent pay for a miss.
4.Laying up on the 1. I don't think that this is possible, but even if it is, its just a move, whereas banking the eight is more aggressive. Whenever possible, you should go for your hole.
5.I also thought for a second about coming off the eight and getting behind the 1, but this shot allows the opponent to move a ball of his choice closer to his pocket; improving his position.