The 883 will do fine and while it does rev a bit over 70, the counter can be switched from 28T to 29T and it will do better with more top end. The 29T is the standard for the 1200 where the 30T is standard on the international models.
I've never had even the slightest problem keeping up with anyone. Some bikes may be quicker, but who keeps up a steady pace of 100+? I can cruise on the highways at 90 (when need be) with no problems.
On the Ride Home from Texas I found my 883 a bit anemic when trying to pull the long grades in MO. Only way to keep up acceleration on the steep ones was to drop down a gear and I would rather back off then pull high revs for a long time, and some of those hills are long. It did fine on flatter stretches. Looking at a 1200 conversion on the XLH but I bought a lowrider for long hauls 65mph in 4th at 3300- 3500 rpm about 2500- 2800 in 5th