Hello and Welcome! 
I am also 6' 4" tall and ride a 1500 Classic. I have had 3 spinal surgeries....2 neck fusions and a lower back hemilaminectomy...L5 S1 which may be enough to keep some from riding at all but I have to say that it was just the opposite for me after I put on the 4 x 1 risers and a riders back rest. It feels like I'm riding in a very neutral position having it set up this way and not uncomfortable for me at all. I'm sure you could easily find your own comfort position on a Nomad with little effort....but that's just my opinion as I'm sure that would be possible with most bikes if you work at fitting the bike to you. Good luck on what ever you decide to buy.
I am also 6' 4" tall and ride a 1500 Classic. I have had 3 spinal surgeries....2 neck fusions and a lower back hemilaminectomy...L5 S1 which may be enough to keep some from riding at all but I have to say that it was just the opposite for me after I put on the 4 x 1 risers and a riders back rest. It feels like I'm riding in a very neutral position having it set up this way and not uncomfortable for me at all. I'm sure you could easily find your own comfort position on a Nomad with little effort....but that's just my opinion as I'm sure that would be possible with most bikes if you work at fitting the bike to you. Good luck on what ever you decide to buy.