well, the Zs were originally designed for the US market. If americans were accepting of female or feminine sounding names for their cars, all 370Zs sold now will still be badged as "FairladyZ". Its purely cuz having numbers and alphabets appealed more to the consumer that they used numerals in the badging. Same for the 240SX/Silvia argument.
anyway, as long as its a Z34, its a Fairlady 370Z. irregardless built LHD/RHD or sold in Japan/USA/EU etc etc., meaning any badge is fine.. just up to user preferences.
Personally i prefer the name Fairlady as cars/boats/planes are all females.. irregardless of how much muscle she packs...
