I ran a flat carpet oval a couple of weeks ago with a 150 foot runline. The rollout everyone used for 13.5 there was a 2.8. So for 160, I would start there at about 2.8, and maybe if that seems a little slow, try 2.9.
The actual numbers really depend on the shape of the track - 150 foot runline with long straights and narrow turns will have a lower rollout than a 150 foot runline track with shorter straights and longer/wider turns. You'll be accelerating and decelerating more on a track with long straights and tight turns, so you'll need a slightly lower rollout for that type of track.
Next month, I will be running the Speedway Spectalaur in daytona in the 4300 class. I think the track will be about 180 with sweaping turns on Ashpalt, what might be a good rollout, this will be my frist run with brushless