Manitunc,
I think the base is fine. When I bought my Vector 3, I was also looking at a Vector 4. The box on the Vector 4 said 2200-2800 models. I checked with Basis, and they said those models require a deeper cup than the 2000-2001 models. If you see pictures of both you can see the cup holding the damping fluid is much deeper on the Vector tonearm designed for the 2200-2800 turntables. I do not think the 2200-2800 model would work on your turntable. Mr. Conti said it would not work on mine
You can also check with Basis. Their service and service attitude is great.
Did you hear a significant difference when you changed from the Rega to the Vector tonearm? For me the difference was stunning, in the best way.
Jim Perry