Hi, I am wondering if any wide glide owners have changed their front wheel and tyre to a 21 X 120 tyre.

Slightly better contact patch, can run a sportier profile, I didn't notice any negatives in the 9 years I rode it with a 120 on the front. 

Just make sure your rim is wide enough, hilly's bike has an aftermarket mag on it- https://www.smtwheels.com/motorcycle-tire-and-rim-size-chart/  -from this chart you require at least 3.25" rim