First off, :welcome:
Second, I have moved your thread to the tech section for hopefully better response, although most of the time it don't matter on TWF.
Third, I'm sure if you have a desent fabricator anything is possible!
Have you found the pure size dimensions between the HD motor vs the RC51 motor? You would think that if you have the 1200cc buell that the 1000cc RC51 would fit!