In general, standard .38 Special cartridges should be OK. I wouldn't use +P loads. Even if a case splits (I've never had that happen in a Victory, but have in other revolvers), it won't do any damage. As these modifications were done in many places (none of them S&W) it might well be possible to find a rechambered Victory with really sloppy chambers that could be more prone to case splitting.

.38 S&W might group a little better than .38 Special, the downside being the availability difficulty and cost of .38 S&W ammunition.