Mr.88-80Q

Wanted to know if the B3 bumpers (yeah the ugly dark grey ones) can be refinished? I found an entire bumper assembly for a $100.00 and it has big scuff on the side... other than that it looks great. I know its a actually a black plastic which is then pained dark grey...I know, my rear bumpers paint is peeling off. I'm wondering if the scuff can be sanded and then prepped for repaint. Have any of you guys done this??? Remember it is the very early ugly grey ones....Thanks guys.