Defrost Help!!!

Ok So I have another question. I figured out that there was no vacuum on the system. (The owner before me didn't have it hooked up at all) So my question is, Can I just hook it up to a "T" off of my brake booster? Or since my 4bbl Carb has a port off of it (the one that typically could run to the auto trans) can I put a line off of that or is that going to affect performance in any way?