That is one extremely sharp looking 260z! I hope it won't bother you to know that your classic Z is not the first in Germany to have a RB powerplant! There was a RB25 powered 280zx there last year. It was a 2+2 no less. Best of luck with your swap!
My S130 did very well cuising at 150MPH (according to my GPS) on the autobahn in Germany. It was rather loud but I could still hear the engine and blowoff valve when I left off the gas. The car pulled hard all the way there.