I'm 6' and 220 lbs. My first motorcycle was an 84 Honda CM250C. In 85 They rebadged it to the Rebel.
Yes, it felt like I was a circus bear most of the time. But I also rode that thing like it was a motogp bike. Great thing to learn on, even if uncomfortable for any longer than half an hour.
A Shadow wont necessarily be any better either, I upgraded to a 750 Shadow Aero, wound up still basically with a half hour time limit. I did ride it longer distances, a few 2 1/2 hour long highway rides, and it was miserable. Mini-apes would likely have fixed a lot of those issues, but I wound up trading it for a 400 horse Camaro before I could test that theory.
Shop around and sit on a bunch of bikes. I wound up sitting on a Suzuki Boulevard C50 and it was much more comfortable than what my Shadow had felt like. Yet it was also a good size for my girlfriend, so it's a bit of an interesting bike.