It's easy to determine what channels are available by looking at the DCA list. However, you also can look at the channel and power level documention also to determine this. Here is a link: https://www.cisco.com/c/dam/en/us/td/docs/wireless/access_point/channels/lwapp/reference/guide/3702e_3702i_pwr_chn.xlsx
As far as UNI2-EXT, if you do have old devices, then this wouldn't work for you. Many newer devices support these channels and isn't an issue. Why would you use 160mhz channel width however, since you would be reducing the number of overlapping channels? This is what you need to look at before determining if 160mhz is the right thing to do in your environment. Do you have devices that even support this?
-Scott
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-Scott
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