Reddit mentions of 1980

Charles Bradley - This cat just dropped his first album only a few years ago. He performs with the Menahan Street Band and together they capture a wonderful sound. It's not the 60's, but it sure sounds like it.

Arthur Conley - is another awesome guy that is overshadowed by his once mentor Otis Redding. Conley is probably best know for his song Sweet Soul Music. He does not have a large catalog of music, but of what there is I like.

Luther Ingram - Great voice and a great sound, this man sings heartache like no ones business. I'm pretty sure the song I linked If Loving You is Wrong (I Don't Want to be Right) is his biggest song, also one of my favorites.

Teddy Pendergrass - I'm going to assume you know who this guy is, but if not enjoy, he's been around a long time and has some real good songs on his own and with his old group The Blue Notes.

William Bell - He's got quite a lot of music and started to record with the legendary label Stax. His stuff is kinda hard to find outside of Best Of's, he does have a re-release of my personal favorite Bound to Happen.

Gil Scott-Heron - Awesome and depressing at the same time is how best to describe this genius of a man. He talks a fair amount about poverty, struggles, abuse, and "the man". Pieces of a Man may be his best known album, but I'm partial to 1980.

I'm going to suggest one group here that gets overlooked by a lot of people. If you ask a hip-hop producer everyone of them will agree that they are a greatly kept secret due to the drum loops taken from these cats.

Skull Snaps - they are a good mix of Bobby Womack and Curtis Mayfield.

I threw in Bobby Womack as well. I assumed since you mentioned Curtis you would know him as well, but why leave it up to chance.