Hi Novaroadie, I'm 6'4 too and i rode a Giant TCR size L. I also have a long torso and relatively short legs. I had no problems with the bike size. In fact, my LBS calculated the settings using a bikefitting program.
good luck and have much fun with your Giant !!

edi: funny to see that it says 03: 47 pm, at my place, it's 11: 47 am, i'll be having lunch soon;