I'm going to be upgrading my externally regulated alternator for an internally regulated one. I bought a conversion kit and am ready to remove my regulator. I have one question. The regulator used to handle grounding everything to the core support. Do I have to create a new ground now that I'm taking the regulator out of the picture?

No, both your original alternator and the one you are adding are grounded through the alternator case. The alternator mounting bolts provide its ground.