Depends on the torque converter you get. A junkyard tranny may or may not have the torque converter with it. If the transmission is still on the junkyard car, chances are the TC is still in it and can be used again. Thoroughly inspect and clean everything, though.
Also, you can not just replace your TC. Since there's debris like you had mentioned, the entire transmission is compromised. Pull a transmission cooler, too, since that will have to be replaced. New coolers are cheap enough you can just buy new though. It's mounted between the radiator and AC condenser.
You can try that Pull-A-Part right by 480, but how it works there is you will have to bring the tools to remove it from a car yourself. That's why it's good to go there with a few friends to help remove it and inspect it. A good transmission place that my friend used and recommended to me when I was looking for some transmission parts for my J-mod is here:
http://www.buckeyetransmission.com/
It's in North Royalton, but shouldn't be more than a 30 minute drive for you.