2 blocks to work?
That's walking distance and that wouldn't even get my legs armed up. Your Connie will never even get up to operating temp so the carbs won't function well, etc., etc.
Like others have posted, there's a MPG break somewhere around 70 MPH or so. I normally cruise at around 60 - 65 (yeah, I'm one of THOSE guys) and get around 45 MPG. I do NOT have Steve's carb mods, but I DO have his 7th gear mod and the cam timing changes for low-end torque. If I work the bike one the back roads the way it was designed for....maybe 35 MPG or so.
It's mostly all in the wrist, but a large windshield can cost you also, it takes fuel to push a big barn door down the highway at speed.
You tire life will vary accordingly also.