I think he is there:
1. Russell
2. Bird
3/4 Cousy/Havlicek (hard to separate)
5. PP ?
While McHale is, next to Bird, my favorite C, he never had to, nor do I think could he, carry a team on his back for the # of years PP did. Nor could he engineer a comeback like PP did vs the Nets in that historic playoff game. McHale was a uniquely talented player at his position, but I think PP's productivity over a longer period of time carries the day for him.