To be honest, you'd be hard-pressed to find chubby guys with big cocks, period. Mainly because the layer of fat on the pelvis decreases the amount of visible inches on a cock depending on how big you are.
It's been said that the best way to make your dick bigger is to lose weight...and that's mostly true.
I've seen, probably two men who were significantly overweight and had above average endowments in my life.