Welcome aboard.
I test drove a stock 2012 5.0 for a weekend before I bought the Z and I thought the power and torque were fantastic. Can't imagine 650 whp.
But as you said, it has to be streetable and reliable power. Enjoy the Z, it's definitely a head turner and you don't see them all over the place. Non auto enthusiasts I find are often curious and inquisitive due to its somewhat rarity and unique aggressive body lines. Again, welcome to the site and enjoy your new 370Z.