Mike,

Let me add an option to what Paul has just said. If you need to increase cast bullet diameter by a few thousandths of an inch, simply "beagle" the mold. Check out Cast Boolits website for tons of info on the subject, but here's the gist: cut tiny strips of aluminum foil and place them between and below the cavities in your mold. This will increase diameter and the very slight out-of-roundness is not a problem. Play with it a little, and occasionally you'll have to fiddle with getting a piece of foil back in place, but it works. Simple, fast, effective.

As for bullet weights, I suggest you consider something in the 180-200g range, which is these British service revolvers were designed for. Lyman's 358430 is widely used in this application, as it has the right weight and a blunt, round nose similar to the original .38/200. Generally speaking, lighter bullets will shoot lower. In my modern S&W Mods. 32-1 and 33-1, which were regulated for 145-46g bullets, I find that 158's still shoot very close to the sights, and that 200's are noticeably higher. I've never tried light bullets, as I'm generally a fan of the "heavy/slow" approach. I find they have less blast & flash, plus they penetrate very nicely. Felt recoil is more of a shove than a snap. I'm shooting my new-to-me Enfield and my newly-returned S&W Victory for the first time later today or tomorrow. Wish me luck! :-)