I like all three of the above^! good choice, first time I've heard the first two, Thanks!
Rap Rock was mostly underground in the 80s and early 90s, didnt gain popularity in the mainstream until the mid-90s, as you've already stated hammer.
I like these two examples of early raprock by Run-DMC.
YouTube - RUN-DMC - King Of Rock
YouTube - Run DMC - Can You Rock It Like This