The only benefit of this conversion is that there are a LOT of tuners who can tune a LS1 type PCM. Very expensive conversion and the tune isn't cheap either. Your better off either learning to tune it yourself by visiting Delcohack or PCMhack as they are known now, they can real time tune the original Delco PCM or they can steer you in the direction of someone who will be able to assist you.
Performance wise there really aren't any gains to be had.