Start a tight patch; being sure the jag is tight on the rod.
Mark the rod with a felt tip to indicate Top Dead Center and a starting point.
Advance the rod until it comes back to Top Dead Center.
Measure the distance traveled from the start mark. That is the rifling twist, one turn in xx inches.
A lot easier than trying to estimate the amount of twist in a foot.
Twist is most likely 14 and that would normally be a twist designed for the lighter/varmint bullets. Most 223's today are going to the 9 twist to stabilize the heavier bullet ranges. If you are after field/varmint use the current twist should be fine for the 40-50-55gr weight bullets. The No.3 in 223 would be a very nice pkg. for varmint or just plain shooting fun. As we say here in the hills of West Virginia, "right handy..."
I think you will find that several years ago the bore diam. of 223 ceased to be mfg. The Win. Mod 43 22Hornet was 223, but long since gone from production, but to be sure you could call or e mial Ruger and verify but would be suprised that it would not be 224 bore.