the radio is a uniden pro538w
OK, good basic radio.
using a radio shack 3 amp
Exact model info would be helpful.
3 amps -should- run a stock radio just fine. If all you are going to do is run the stock radio out of the box, no other accessories, you should be fine. Do not have some hackjob "peak/tune" done, that'll increase power consumption probably beyond what the power supply will handle.
and I will be using a Firestik 2' (61cm) Single Roof Mount "NGP" Kit Complete (Black) 2' No Ground Plane CB Antenna Kit
i want to use this as a base station
That's going to be a poorly performing setup due to the antenna.
An efficient CB antenna will be about 8 1/2 feet tall, or longer if you want better performance. Trying to cram that into a 2 foot tall antenna is going to result in disappointing performance. If your location and budget allows, you should really consider a better antenna.
Don't overlook the other parts you'll need, like coaxial cable to connect the radio to the antenna, roof mounting, grounding, etc.