How do you know?
They have a -54 Part Number
The crank pin nut is up higher . . .
You can run them in your ironhead and make it a "stroker", but you have to install the later (XL) Sportster sprocket shaft, and to do that, you must cut off a flange on the left flywheel, or your flywheels will be too wide and won't fit in the cases . . . or something like that ?