I guess I would have to ask, how does it shoot? Have you tried a variety of cast and jacketed loads thru it to see what kind of accuracy you are getting, especially compared to your other four rugers? Jacketed bullets tend to shoot better in an slightly oversized bore, compared to cast. If accuracy is good, then it is really a non issue. If accuracy is substandard, and If the bore is .433, and the throats are significantly smaller, then having a local machine shop open them up might be the cheapest, easiest route. Another thing to consider is I believe when Ruger receives an older 3 screw gun in for repair, they automatically perform the updated lock work conversion on it.
Larry