So you’re a big guy and you’re worried about looking silly on a small bike. I have a buddy who’s about the same, rides a 400cc dual sport and laughs that he sometimes feels like a circus bear riding a bicycle. Whatever, he still riding the crap out of the bike and having a blast.
A guy your size might have a valid reason for stepping straight up to a 500cc bike, bypassing the 250-stage. But otherwise, I think all the start-small advice on this site applies equally.
WAY more important than how you look on the bike is how you feel on the bike. I think it’s important to sit on lots of bikes and see what you think. I’d include the big dual sports (KLR 650 and such) in the mix as well.
As for the 883, I don’t think it’s the worst choice. My first bike was a 94 883. In stock form, it’s very well balanced and surprisingly underpowered for it’s engine size. Not that you’ll notice it, as it has an awesome feel and sound. It’s really fun to just cruise and when you get the itch to twist the throttle, it powers up in a satifying manner but then runs out of steam before you can get into too much trouble. It’s also one of the few bikes that you can buy in 883 form and then in a few years drop another $1k into it and pump the engine up to 1150-1200ccs.
I found the biggest issues with the 883 for a beginner were the weight (which is only an issue at low- or no-speed) and the rear brake sensitivity — it’s very easy to lock it up in anything close to a panic situation. Learn to handle a lock up and to always use the front brake and you mitigate that issue.
Have fun looking and take it slow.