Yeah, Cowens did win two titles and an MVP. That's more than a lot of players on that list can say.
And 8 All-Star appearances as well. There is no way he should be bumped from the top-50 in favor of probably 4-5 names on that 'new' list.
I would definitely keep Cowens, Sam Jones and probably Clyde Drexler and Pete Maravich in my Top-50.
Walton is tough. When he played, he was brilliant. Two rings. But despite a 13-year career, he only played in 468 regular season games. He only managed to play 60+ games in 3 of his seasons. If he HAD been able to stay healthy, he might be one of the top tiny handful of greatest NBA players of all time. He's definitely on that list for college players. But because of the limited size of his NBA career, I can see slipping him off the top-50.
I would not include Miller, Nash, or Iverson in my top 50 and Curry seems way too early to include in it. I'm iffy on Ray and Kidd.