In good conscious I cant think of how that would be a good ongoing process to move forward with. What I would do is start an overhaul and merge scenario where you identify the most valuable unique content within the site and start merging less valuable content pages with stronger ones. As well as 301 any old pages to like items or the home page as well as make sure 404's and 410'are in place as well.
With that many pages I know it can be a daunting task to think about but if you truly care for the site and it seems that you do I would not take this approach as it can lead to further damage down the road. I would be trying to make sure I do not get hit again by P & P.
In the end if it seems like a spammy or fishy tactic it probably is or will be at some point.
Good luck my friend