Disclaimer: I am not an expert on muscle bikes, or a close follower of that market.
However: My general understanding is that if it's not a Stingray/Krate (or, for some people, a Raleigh Chopper) it's not gonna be worth the big bucks. Like I said, I'm not an expert, so if this Columbia happens to be a rare model/color and someone has a jones for that, I could be wrong.
There is one potentially valuable part on that bike, and that's the SA shifter, even with the rust. SA people are legion and some of that crosses over. If I were you, I would clean up the bike, get a period-correct one speed coaster-brake rear wheel, ebay the shifter and original rear wheel, and sell the bike locally for 150-250 depending on market.