Agreed - shorter fuselage is always the worst case for engine pitch-up effects due to the reduced moment arm of the tail surfaces.
737 maximum engine ratings are limited on the shorter models for the same reason. I didn't work the NG, but on the 'classic'
737-3/4/500 series, the -300 and -500 models had a physical throttle block to prevent full throttle operation (the engines were common with a common rating). Otherwise under certain conditions, if you firewalled the throttle the engine pitch-up moment could be greater than what the tail surfaces could overcome.