I'm considering diving deeper into old hip hop/rap.
In that case maybe you want to go back to the very beginning. Try; Big Youth - Screaming Targets.
It won't sound like the hip hop you're used to hearing, but it's where that all began. Duke Reid, Sir Coxsone Dodd, Lee "Scratch" Perry, Big Youth, I-Roy, U-Roy, Prince Far-I...
These guys invented improvising lyrics (they called it "toasting") over musical tracks (the dub - instrumental - B sides of Jamaican 45's). All modern hip hop can be traced back to these Jamaican pioneers. They started in the 60's, but the guys who did it in the very early 70's and released "toasting" singles and albums (it was all done live before that, never pressed on records for release - just like early hip hop) were the seeds of the New York hip hop movement of the late 70's.