My K22, K87xx is a real rat but it shoots better than any new 22 revolver I have owned.
I would get it restored if I thought there is a Gunsmith that could do it right at a reasonable price. If I did, it probably would not shoot as well afterwards.
Someone is pulling your leg. You could shoot 12 rounds loaded with blackpowder without jamming the 66 so bad it would not shoot.
P.S.
I own a 66, 2.5".