If you are an Aircraft Commander in a current C-130 model, then there shouldn't be any follow-on training. You are qualified to fly the herc. If you go to a Guard unit, the chances are you will start off in the right seat. This gives the unit a chance to evaluate you and see what kind of guy/pilot you are. It is not a knock against you personally, this happens to everyone. After being in the right seat for a while (time frame can vary greatly), the unit will cert you, again, as an AC.
Although, you timing may not be the best. We find out the results of the BRAC this week. If it goes thru as is, there may be a shortage of C-130 cockpits in the Guard/Reserve. Everyone keep their fingers crossed that the Herc world is not turned upside down. We are hearing the results could be posted as early as Thursday evening.