Back when those were new there were a couple of years I owned both a touring bike and a sporty road bike. I found longer distances much more comfortable on a longer wheelbase bike with wider tires. By far.

To the extent that I'd have picked a LeTour or Traveler ('75 & up) over a Paramount for a century (New England, Nebraska, Colorado, whereever) unless I'd logged a couple thousand miles in the season.

That said, there's absolutely nothing wrong with a Ross Signature. It might be a little tighter than I'd like, but it should be fine for metric & imperial century distances.

My preference would include eyelets for a rack, because I've known the weather to change when I was 40 miles from home.