New seat and handlebars can mage a huge difference.

 

The only difference is the seat height and the Street Glide has 1" lower REAR shocks.
The front springs are the same on all models. They are NOT shorter on a Street Glide. It's practically the same bike just with different trim.

Get a take off seat and 12" street glide rear shocks on ebay for next to nothing and you'll have a Road King that "sits like a Street Glide".

Stock Street Glide seats suck BTW. If you can find one, get an 08 Road glide seat. It has a narrow nose, is lower, better shaped, and is 2X more comfortable.

lp