You can go on Youtube and see Chamberlain. I saw him in the early 70's and believe he was clearly better than Kareem. A lot more physical and athletic. He was like a bigger and much more skilled Dwight Howard. If he played in the 90's during the big man era, he would totally dominate Ewing. He would be better than the other centers with Hakeem, Kareem and a young Shaq coming in 2nd, 3rd and 4th.
Edit: people who never saw Wilt play may not realize how mobile he was. Ewing was nowhere near his level. Imagine LeBron James with about 5 more inches. No, not quite that mobile. But he was a track star before he played basketball and was extremely athletic.