Can't just transport players across eras like that. If Oscar had the privileges of today's athletes he'd be much better too.
But for what he was in his time period, Oscar was a skilled post player who used his size to easily shoot over smaller defenders, had an elite mid range game, a creative finisher, great rebounder and had elite court vision. So-So defender until he got to Milwaukee and became a more vocal defensive leader (as attested to by his teammates)
I look at his skills for what they are and see a better basketball player than Isiah Thomas. With his size and skill Oscar would translate extremely well in any era. Him and Wilt are the obvious older legends that it's easy to see dominant across time.