From an interviewan interview with Eric Walker, who played Mace Towani:
The first Star Wars name George Lucas came up with was Mace Windu; his name is featured in one of the first drafts of A New Hope. Was your character Mace Towani named after him?
No. Mace Towani is Star Wars first Mace. He used the name again with Samuel Jackson because he liked the name. There is no truth to the rumor that Mace Windu was in the first drafts of A New Hope. Mace Windu was never mention in The Journal of the Whills or the first drafts of A New Hope. All that was added later. But if you know anyone that has one of the original scripts from 1973-1976 and not revised ones, they will tell you that Mace was added later. In fact a lot of Star Wars writers have done articles in magazines calling Eric Walker Star Wars first Mace. You can find the articles in the official Star Wars magazine of Germany and the U.K.