there's a thread going about offset ( raked ) steering head bearings on a Sporster on the HDRCGB forum at present.
I'd feel these are fundamentally unsound because;
(a) there is no practical value to fitting extended forks to a Sporty anyway
(b) having your steering geometry dependent on something pushed into the steering head is counter to the usually accepted principle that the frame's main purpose is to provide a fixed relationship between the wheels, and jig construction provides the best control of this at construction stage
(c) there's a comment about 'the misalignment being distributed over 180 degree' which frankly, I can't make any sense of