I believe it will.
But if you changed out the trigger controls to make it a LEM, then I am not sure it would still be considered a SSP gun, but rather an ESP gun. The IDPA specs for the box are 8 ¾” x 6” x 1 ⅝”.
HK USP 9 Expert (Specifications)
Caliber: 9mm Luger
Action: Semi-Automatic
Overall length: 7.94 in
Overall height: 5.35 in
Overall width w/lever: 1.26 in
Barrel length: 5.19 in
Sight radius: 6.22 in
Sights: Adjustable
Weight: 33 ounces
Trigger: DA/SA