I believe this is Southwest corner of Blackstone and Barstow.

I agree.

K-Mart

It would appear that this Kmart was either torn down or heavily remodeled to become a Circuit City at some point. It is now "Furniture City".

The Safeway, on the other hand, remains recognizable as "Furniture City Outlet".

This is the K-Mart where our mother would buy our Halloween costumes. Near the entry, they had a deli counter that sold pretty good sandwiches.

Store 4068. A very early Kmart from the mid-60s.
Somewhere, I have a training video from KIH that shows how the Super Subs were made.
I think it involved honey ham, salami, and bologna, with a mixture of mustard and mayonaise. Paper-thin sliced onion, sliced tomato, lettuce and local variations, such as peppers. White bread bun.

Okay JB, now you made me hungry for one of those. What you described sounds exactly what I remember. That training video would be fun to see.