Not as good. Joe would not be a headhunter in there. His bodywork would have a bigger effect on Mavrovic than head shots. Lennox rarely threw to the body & certainly did not test an opponents ability to absorb body punishment. Joe Louis would. The other factor is I felt that Mavrovic could read everything Lewis was doing in there. Louis did not telegraph at all---and I think those kinds of punches take a bigger toll. I do not think enough of the Mavoric offensive toolset to thwart a guy like a Joe Louis.
Yeah I was watching that fight last night and saw that he took huge shots from Lewis and wondered how far he'd get with Joe Louis, who certainly was smaller than Lennox Lewis, but there's debate on who hit harder. But I agree with your view.