The copy that I have credits the July 25, 1967 first draft to Spinrad and Coon from a story by Spinrad. It is identical in every other way to the Amazon.com preview for the version that Spinrad is now selling and includes this bit that was quoted in another thread...
I haven't paid the $9 to buy the full version for further comparison, but from what I have seen the only difference is the absence of Coon's name.
"Scene 23: ANGLE TOWARD THRONE
"As Bayne enters. Dressed in flowing robes, looking quite
regal, Bayne is a largish, heavy man of great dignity...and
just as obviously a Negro from earth."
So it doesn't look like Spinrad's original script actually was intended for Mr. Berle. it was probably only the Coon rewrite version that introduced that aspect.
I haven't paid the $9 to buy the full version for further comparison, but from what I have seen the only difference is the absence of Coon's name.