I have a fatboy with a 21" spoked front wheel with 140 tire and a stock fatboy rear wheel and tire. I think it looks good but i added heritage bags so the rear wheel and tire is mostly covered when looking at it from the side.
Ya i would think it would just look like a Night train or softail custom just with an FL front end instead! I dont know why you would want to do this tho! I love the way the fat front wheel and tire handle! Much more stable then that skinny *** 21 i had on my train! After buying my new Fatboy Lo 2 weeks ago and feeling how much better and comfy it is compared to my Train was i swore to myself i would never go back to a skinny wheel and foot pegs! Im now a converted Foot board and fat tire guy! soooo comfy!