Of the two you listed the heritage and go with the 158.
Since you clearly said a freestyle oriented powder board (ie that does well in powder but also rides switch well etc) that looks like a very good choice to me.
I ride a 157 proto at 170lbs and love it in powder as long as its not crazy deep (40cm or less).
The obligatory picture.
That was in sidecountry and it was maybe 30cm of powder. I floated through easily with minimal effort even in these less steep areas.
ETM you are a Hokkaido powder addict
. While you are right that no twinish deck will perform superbly in powder, in this weight range the C2BTX gives really good float (not effortless but good float). Plus what they call epic powder is more like an OK day here in Japan.
All in all I think you are in the right area with the 158 heritage
Of course there are plenty of other good boards you might consider too.