What size turbo?

I am very interested in putting a turbo on my 225 slant six, but after doing some research I am still not sure as to the proper size I should be looking for. I am trying to get the parts together right now and have found an almost new T3/T4 turbo for $85. I was just curious whether or not this would be a good option for me, and if not what I should be looking for. I am not interested in racing this car, I just want to get a little more out of it as a daily driver.