I don't know the twist rate of the barrel but I would put the value of the rifle in excellent shape at around $500 in mint shape because the 220 Swift is fairly rare and popular. A 30-06 in the same shape would probably go for $400.
I just bought a 270 Win for $450 with a custom stock that was beautiful but had bedding problems and rings and a scope. I follow them on Gunbroker and some dealers ask a lot more for a Ruger model 77 with tang safety in excellent condition but they don't sell and just keep getting relisted.
It's most probably 1:14. Best thing to do is measure it with a cleaning rod. Use a tight patch and start the rod in the breech. Once it's in the barrel a few inches, put a dot on the rod near the handle with a marker, at dead top center and another mark where the rod is entering the barrel. Then push the rod in until the dot near the handle comes back to the top again and make a third mark on the rod where it is entering the barrel, just like you did the second mark above.
Push to rod all the way out, remove the patch and withdraw the rod. Finally measure the distance between the two marks at the front of the rod and that will be the number of inches required for a full revolution.
As I said at the beginning, my bet is that it will be 14 inches, making it a 1:14 twist.