I need to preserve links after a node has been deleted, is it possible?
I assume that you are talking about links that are linked to the deleted object. I would actually add an invisible object with the same size / location as the deleted object, and link to the hidden object.
I managed to get a link to display without ports set at one stage, but that was by adding manual points to the line. I think this behaviour was changed at some stage.
You could set the GoPort.ClearsLinksWhenRemoved property to false.