The KLN-89B isn't WAAS-capable so it's virtually certain that it won't meet the GPS accuracy and integrity requirements for ADS-B Out. As far as I know, Honeywell doesn't have an upgrade path to add WAAS to the 89B so you might want to look at other options.
Hope this helps,
RV-7 skin, bones, muscle and heart complete, nervous system in progress
Nashua, NH (KASH)
Putting the "slow" in slow-build since 2004!