ideal chain replacement for Redline monocog 29er
I think the ideal chain replacement would be the Sram PC-1.  I use this on my single speed mountain bike and stand up and crank on it with no issues what so ever.  The installation is very straight forward and the master link is very easy to use.  I would definitely not recommend an old multi-speed chain for this application mainly because the PC-1 is so affordable and effective.  The one issue that I do have with the PC-1 is that the master link is a bit wide and it does rub a bit on the bashguard that is installed on my Sram crankset, but it does not affect performance in any way.