i traded mine , but when i had it it was pretty comfortable. i always had the seat all the way back and that was comfortable leg wise and head wise it was allright (mine didnt have a sunroof, you lose about 2 inches of headroom if you get a sunroof one). i'm 5'11 btw.
i suppose for someone 6'4 you could probably be ok just maybe, but no one will ever be able to sit behind you (whenever someone had to sit behind me , with 4 people in the car, i had to scoot the seat up so much that i was banging my knees on the console). anyways, i suggest you sit in one.
a friend of mine has 350z, and it is more or less the same in every dimension. if there is a nissan dealer nearby you could try that just to approximate
also to the people suggesting putting the seat lower. that probably isnt a good idea, as the blind spots in the car are awful. you'd have to have a really tall torso and imean freakishly tall, to get away with putting it all the way down.