Actually...Forget I said anything. Sure, the Triumph and elderly Honda may naturally press ahead slightly, but you and the prewar Norton should be a fine match. What model of Norton is it, I wonder? Also, your Enfield has superb engine braking. I had zero issues with anything like brake fade in the Appalachians. Of course, I have the 5-speed, with basically that extra gear between 3rd and top. A four speed with that BIG stretch between 3rd and 4th may be more of a wind-up challenge, especially getting up steeper grades.