I have gotten great advice on our K75 here in old school. I have held a steady position that we are a "big tent" here in old school, if you think you belong here, you probably do. All that said, I don't really think anything with electronic fuel injection and ignition is really "old school".
Like you said, my wife K75 keeps up with traffic fine. My R100 will too, although you have to work the gear box a little more. These bike are geared nicely, the gearing combinations limit the top speeds at about 100 to 115. The power is moved down to where you really need and use it.
I have a '91 GS500E, 39HP at the wheel. It does fine too.
A stock BMW '55 R50 is another story, even an early 70s R60 or R75 can run out of breath with Interstate speed limits of 70 or 75. Yeah, they will get there, but there isn't much left after that.
Have you visited ride reports lately ?. click HERE