I'm nearing completion of a new shop and need some advice on lighting. The shop is 18' x 24' and has a cathedral-type ceiling, 8" pitch, the peak along the 18' dimension. The lowest wall height is 11', and the peak of the ceiling is about 18 1/2'. It is wired for 4 fixtures on each roofline, switched independently. My plan is to install a 4 bulb, 4' High Bay fixtures at each of the 8 boxes. Will T8 fluorescents be enough considering the ceiling height or are T5's excessive? 5000K vs 6500K bulbs? Thanks for any advice you can offer.