you wont be comfortable in a sportster.
if you mean bigger frame and not bigger engine.
there are plendy of smaller engines with bigger frames ou there.
But it apprears you have tunnel vision with Harleys.
If you are going to ride with your wife on the back, them women prefer reliable bikes....and with a Honda for example, the oil is designed to be on the INSIDE of the engine.
Best of luck.
If I were you I would look at the larger Harleys (if that is what I wanted in name brand). Look at the larger Hondas and Yamahas. All manufacturers build larger bikes than a sportster. you height may dictate something other than a cruiser style but that is where most people turn.