I bought someone a project rig and need a hand.

I was told it was a 350 block from a 79 el camino
automatic turbo 350 tranny

The starter went out and now the one I picked up from NAPA worked a couple times, then caught every now and then, now just makes a horrible grinding noise if i crank it.

What info do i need to post for someone to figure out what starter i need??

Thanks in advance!