Start with Dreadnaught.
It should appeal to both of you.
(I'm guessing you've already seen it).
I had to look it up, I'm assuming you mean the 1981 kung fu flick? I watch a LOT of movies and I had never even heard of Dreadnaught. It may be good but I'd be hard pressed to put it in the "must-see classic" category category KD seems to be going for if it's such a niche movie. Although maybe the martial arts angle is appealing.
Either way, I think YK has a good point. Even if you don't let it go entirely, maybe you guys can switch off movies where you each pick one you really like. That way you're trying to meet him half way by sharing and not just "being the old man" and forcing him to experience things you liked.
Maybe use those as occasions to talk about why the movies you chose were so influential either to you or to movies as a whole. After watching his movie choices you can get into discussions about what he likes about them and then see if there are "better" movies that have similar elements.