I was trying to figure this out myself. I have a 53cm 08 Bianchi Pista and it fits perfectly. I'm about 5'8 and my inseam is 30. I think you might need a 52 considering the standover on the 54 Godzilla is 32.25

I just noticed that you said you have your saddlepost high. So the 54 might work, but from my research and from what i've heard the Godzillas run big