This is really a great looking SERK.
Did you replace the master cylinder or anything else in the front brake system when you fitted the Brembo brakes?
Have done the Brembo swap on a few bikes and done it with and without changing the master cylinder. It works either way. There is a difference in lever feel when you swap the cylinder though. It's something you can used to either way but the lever feel and travel are more as you expect them when you use the later model master cylinder with the later model calipers.
When using the older master cylinder with the newer caliper each bike I've done it got full braking a little later in the pull and with a little harder pull. The larger bore size of the new master cylinder does make a little bit of difference. I can't tell you it's a "must do" though. Just a slightly better feel. It's not so profound or significant I even did it on both of mine. The SERK has Brembos and the Brembo era master cylinder. My Road Glide has Brembos and the older master cylinder. Operation is very good on both bikes though the feel is slightly different. You do want to change the rotors though.