John Prewitt poster or print

My dad was heavy into Cowboy Action Shooting before he passed away. This was his poster or print. I could not find anything on this John Prewitt poster or print. I might have the name wrong, it might be Jimmy or Jolin. Dimensions are 16" x 20" without the frame and 17 1/2" x 21 1/2" with frame. I am trying to find out value and description? Thank you for your assistance in this matter. Rob

 

Looks more like Jim Prewitt, but using that name in search didn't get me anywhere.

 

If you don't see tiny dots under magnification, this may be an original drawing. It looks like charcoal to me.

It's nicely done, but could be the work of a talented student or amateur.

 

Some pen and ink work in there, looks like.

 

It looks like a sharpie marks-a-lot sketch. If so, don't get it in sunlight or it will fade. If you stack it flat to protect it, it could leech ink onto the next piece, so be sure to pad it with acid free paper. It looks nicely drawn to me.