I love Ruger single shots. I have 3 #3's, 22 hornet, 30-40 krag, and
45-70, and a #1 standard in 3006.
The 45-70 is probably my favorite brush gun.
I'd leave the 223 alone. If you want a short 243, look at the #1 sporter, it has a 22" barrel, same as the #3. It's available in 243. My friend has one in 270. Its a real pretty gun, and shoots well.