Basically, the answer to your question is "no" although there may be a few of the accessories from back in the day still kicking around. These would include an extended barrel (which may need to be fitted), and fully adjustable rear sights (one made by S&W, the other by MMC). You're probably stuck with the magazine capacity, as (and I may be corrected on this) I don't recall an extended mag ever being available.
You don't specify the nature or severity of your "accuracy" problem, but there are plenty used 39-2 parts out there that when substituted for yours might improve the situation. A different barrel, bushing, or slide could help, but that's fairly expensive experimentation that may just as likely yield no tangible results. One thing to check is that your rear sight fits tightly and is not shifting around at all in between shots.
