I just figured it out. My base shear was huge because of an issue with the joists implemented within the model. I don't know why, but they were making my seismic weight way too large.
I removed them all and obtained a fundamental period around 1.3 sec. To answer you question, my scaling...
This model seems like a mess, however I'm just trying to verify my base shear through a response spectrum analysis. I've attempted it several times, and at first I was getting a base shear of ~200000kN, then I ended up decreasing that to 80000kN (still ridiculously large), and finally back up to...
