I also have a Century IIB, and pleade forgive my naivety as this isnt something I have looked into much, but is it possible a) on a Piper Archer II to upgrade to one of the similar age auto-pilots that maintain altitude b) find a company that might 'upgrade' an old piece of kit to something equally old, but a bit more useful? Obviously we have the servo units and other components for horizontal movements, but wasnt sure if the kit was in place for vertical movement (servo's etc).
The group I am in is saving up for some bodywork / re-spray work so I am looking at this from am a very limited budget point of view at the moment, hence there are no options for spending thousands on more modern systems
As an aside my Century IIB, will often do a 30 deg angle of bank turn, I am sure I read that it was supposed to be limited to a rate 1 turn. Does anyone have any similar experience of this?